header

Profile


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Prof. Dr. Torsten Wolfgang Kuhlen
Room K107
Phone: +49 241 80 24783
Fax: +49 241 80 22134
Email: kuhlen@vr.rwth-aachen.de



Publications


Calibratio - A Small, Low-Cost, Fully Automated Motion-to-Photon Measurement Device


Sebastian Pape, Marcel Krüger, Jan Müller, Torsten Wolfgang Kuhlen
10th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS), 2020
pubimg

Since the beginning of the design and implementation of virtual environments, these systems have been built to give the users the best possible experience. One detrimental factor for the user experience was shown to be a high end-to-end latency, here measured as motionto-photon latency, of the system. Thus, a lot of research in the past was focused on the measurement and minimization of this latency in virtual environments. Most existing measurement-techniques require either expensive measurement hardware like an oscilloscope, mechanical components like a pendulum or depend on manual evaluation of samples. This paper proposes a concept of an easy to build, low-cost device consisting of a microcontroller, servo motor and a photo diode to measure the motion-to-photon latency in virtual reality environments fully automatically. It is placed or attached to the system, calibrates itself and is controlled/monitored via a web interface. While the general concept is applicable to a variety of VR technologies, this paper focuses on the context of CAVE-like systems.

» Show Videos
» Show BibTeX

@InProceedings{Pape2020a,
author = {Sebastian Pape and Marcel Kr\"{u}ger and Jan M\"{u}ller and Torsten W. Kuhlen},
title = {{Calibratio - A Small, Low-Cost, Fully Automated Motion-to-Photon Measurement Device}},
booktitle = {10th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (SEARIS)},
year = {2020},
month={March}
}





Joint Dual-Tasking in VR: Outlining the Behavioral Design of Interactive Human Companions Who Walk and Talk with a User


Andrea Bönsch, Torsten Wolfgang Kuhlen
IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE), 2020
pubimg

To resemble realistic and lively places, virtual environments are increasingly often enriched by virtual populations consisting of computer-controlled, human-like virtual agents. While the applications often provide limited user-agent interaction based on, e.g., collision avoidance or mutual gaze, complex user-agent dynamics such as joint locomotion combined with a secondary task, e.g., conversing, are rarely considered yet. These dual-tasking situations, however, are beneficial for various use-cases: guided tours and social simulations will become more realistic and engaging if a user is able to traverse a scene as a member of a social group, while platforms to study crowd and walking behavior will become more powerful and informative. To this end, this presentation deals with different areas of interaction dynamics, which need to be combined for modeling dual-tasking with virtual agents. Areas covered are kinematic parameters for the navigation behavior, group shapes in static and mobile situations as well as verbal and non-verbal behavior for conversations.

» Show Videos
» Show BibTeX

@InProceedings{Boensch2020a,
author = {Andrea B\"{o}nsch and Torsten W. Kuhlen},
title = {{Joint Dual-Tasking in VR: Outlining the Behavioral Design of Interactive Human Companions Who Walk and Talk with a User}},
booktitle = {IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE)},
year = {2020},
month={March}
}





Towards a Graphical User Interface for Exploring and Fine-Tuning Crowd Simulations


Andrea Bönsch, Marcel Jonda, Jonathan Ehret, Torsten Wolfgang Kuhlen
IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE), 2020
pubimg

Simulating a realistic navigation of virtual pedestrians through virtual environments is a recurring subject of investigations. The various mathematical approaches used to compute the pedestrians’ paths result, i.a., in different computation-times and varying path characteristics. Customizable parameters, e.g., maximal walking speed or minimal interpersonal distance, add another level of complexity. Thus, choosing the best-fitting approach for a given environment and use-case is non-trivial, especially for novice users.

To facilitate the informed choice of a specific algorithm with a certain parameter set, crowd simulation frameworks such as Menge provide an extendable collection of approaches with a unified interface for usage. However, they often miss an elaborated visualization with high informative value accompanied by visual analysis methods to explore the complete simulation data in more detail – which is yet required for an informed choice. Benchmarking suites such as SteerBench are a helpful approach as they objectively analyze crowd simulations, however they are too tailored to specific behavior details. To this end, we propose a preliminary design of an advanced graphical user interface providing a 2D and 3D visualization of the crowd simulation data as well as features for time navigation and an overall data exploration.

» Show Videos
» Show BibTeX

@InProceedings{Boensch2020b,
author = {Andrea B\"{o}nsch and Marcel Jonda and Jonathan Ehret and Torsten W. Kuhlen},
title = {{Towards a Graphical User Interface for Exploring and Fine-Tuning Crowd Simulations}},
booktitle = {IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE)},
year = {2020},
month={March}
}





Talk: Insite: A Generalized Pipeline for In-transit Visualization and Analysis


Simon Oehrl, Jan Müller, Ali Can Demiralp, Marcel Krüger, Sebastian Spreizer, Benjamin Weyers, Torsten Wolfgang Kuhlen
NEST Conference 2020
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Neuronal network simulators are essential to computational neuroscience, enabling the study of the nervous system through in-silico experiments. Through utilization of high-performance computing resources, these simulators are able to simulate increasingly complex and large networks of neurons today. It also creates new challenges for the analysis and visualization of such simulations. In-situ and in-transport strategies are popular approaches in these scenarios. They enable live monitoring of running simulations and parameter adjustment in the case of erroneous configurations which can save valuable compute resources.

This talk will present the current status of our pipeline for in-transport analysis and visualization of neuronal network simulator data. The pipeline is able to couple with NEST along other simulators with data management (querying, filtering and merging) from multiple simulator instances. Finally, the data is passed to end-user applications for visualization and analysis. The goal is to be integrated into third party tools such as the multi-view visual analysis toolkit ViSimpl.




Voxel-Based Edge Bundling Trough Direction-Aware Kernel Smoothing


Daniel Zielasko, Xiaoqing Zhao, Ali Can Demiralp, Torsten Wolfgang Kuhlen, Benjamin Weyers
Computers & Graphics
pubimg

Relational data with a spatial embedding and depicted as node-link diagram is very common, e.g., in neuroscience, and edge bundling is one way to increase its readability or reveal hidden structures. This article presents a 3D extension to kernel density estimation-based edge bundling that is meant to be used in an interactive immersive analysis setting. This extension adds awareness of the edges’ direction when using kernel smoothing and thus implicitly supports both directed and undirected graphs. The method generates explicit bundles of edges, which can be analyzed and visualized individually and as sufficient as possible for a given application context, while it scales linearly with the input size.

» Show BibTeX

@article{ZIELASKO2019,
title = "Voxel-based edge bundling through direction-aware kernel smoothing",
journal = "Computers & Graphics",
volume = "83",
pages = "87 - 96",
year = "2019",
issn = "0097-8493",
doi = "https://doi.org/10.1016/j.cag.2019.06.008",
url = "http://www.sciencedirect.com/science/article/pii/S0097849319301025",
author = "Daniel Zielasko and Xiaoqing Zhao and Ali Can Demiralp and Torsten W. Kuhlen and Benjamin Weyers"}





Feature Tracking Utilizing a Maximum-Weight Independent Set Problem


Andrea Schnorr, Dirk Norbert Helmrich, Hank Childs, Torsten Wolfgang Kuhlen, Bernd Hentschel
The 9th IEEE Symposium on Large Data Analysis and Visualization
pubimg

Tracking the temporal evolution of features in time-varying data remains a combinatorially challenging problem. A recent method models event detection as a maximum-weight independent set problem on a graph representation of all possible explanations [35]. However, optimally solving this problem is NP-hard in the general case. Following the approach by Schnorr et al., we propose a new algorithm for event detection. Our algorithm exploits the modelspecific structure of the independent set problem. Specifically, we show how to traverse potential explanations in such a way that a greedy assignment provides reliably good results. We demonstrate the effectiveness of our approach on synthetic and simulation data sets, the former of which include ground-truth tracking information which enable a quantitative evaluation. Our results are within 1% of the theoretical optimum and comparable to an approximate solution provided by a state-of-the-art optimization package. At the same time, our algorithm is significantly faster.

» Show BibTeX

@InProceedings{Schnorr2019,
author = {Andrea Schnorr, Dirk Norbert Helmrich, Hank Childs, Torsten Wolfgang Kuhlen, Bernd Hentschel},
title = {{Feature Tracking Utilizing a Maximum-Weight Independent Set Problem}},
booktitle = {9th IEEE Symposium on Large Data Analysis and Visualization},
year = {2019}
}





Influence of Directivity on the Perception of Embodied Conversational Agents' Speech


Jonathan Wendt, Benjamin Weyers, Jonas Stienen, Andrea Bönsch, Michael Vorländer, Torsten Wolfgang Kuhlen
19th ACM International Conference on Intelligent Virtual Agents (IVA), 2019
pubimg

Embodied conversational agents become more and more important in various virtual reality applications, e.g., as peers, trainers or therapists. Besides their appearance and behavior, appropriate speech is required for them to be perceived as human-like and realistic. Additionally to the used voice signal, also its auralization in the immersive virtual environment has to be believable. Therefore, we investigated the effect of adding directivity to the speech sound source. Directivity simulates the orientation dependent auralization with regard to the agent's head orientation. We performed a one-factorial user study with two levels (n=35) to investigate the effect directivity has on the perceived social presence and realism of the agent's voice. Our results do not indicate any significant effects regarding directivity on both variables covered. We account this partly to an overall too low realism of the virtual agent, a not overly social utilized scenario and generally high variance of the examined measures. These results are critically discussed and potential further research questions and study designs are identified.

» Show Videos
» Show BibTeX

@inproceedings{Wendt2019,
author = {Wendt, Jonathan and Weyers, Benjamin and Stienen, Jonas and B\"{o}nsch, Andrea and Vorl\"{a}nder, Michael and Kuhlen, Torsten W.},
title = {Influence of Directivity on the Perception of Embodied Conversational Agents' Speech},
booktitle = {Proceedings of the 19th ACM International Conference on Intelligent Virtual Agents},
series = {IVA '19},
year = {2019},
isbn = {978-1-4503-6672-4},
location = {Paris, France},
pages = {130--132},
numpages = {3},
url = {http://doi.acm.org/10.1145/3308532.3329434},
doi = {10.1145/3308532.3329434},
acmid = {3329434},
publisher = {ACM},
address = {New York, NY, USA},
keywords = {directional 3d sound, social presence, virtual acoustics, virtual agents},
}





Passive Haptic Menus for Desk-Based and HMD-Projected Virtual Reality


Daniel Zielasko, Marcel Krüger, Benjamin Weyers, Torsten Wolfgang Kuhlen
IEEE VR Workshop on Everyday Virtual Reality (2019)
pubimg

In this work we evaluate the impact of passive haptic feedback on touch-based menus, given the constraints and possibilities of a seated, desk-based scenario in VR. Therefore, we compare a menu that once is placed on the surface of a desk and once mid-air on a surface in front of the user. The study design is completed by two conditions without passive haptic feedback. In the conducted user study (n = 33) we found effects of passive haptics (present vs- non-present) and menu alignment (desk vs. mid-air) on the task performance and subjective look & feel, however the race between the conditions was close. An overall winner was the mid-air menu with passive haptic feedback, which however raises hardware requirements.

» Show BibTeX

@inproceedings{zielasko2019menu,
title={{Passive Haptic Menus for Desk-Based and HMD-Projected Virtual Reality}},
author={Zielasko, Daniel and Kr{\"u}ger Marcel and Weyers, Benjamin and Kuhlen, Torsten W},
booktitle={Proc. of IEEE VR Workshop on Everyday Virtual Reality},
year={2019}
}





A Non-Stationary Office Desk Substitution for Desk-Based and HMD-Projected Virtual Reality


Daniel Zielasko, Benjamin Weyers, Torsten Wolfgang Kuhlen
IEEE VR Workshop on Immersive Sickness Prevention (2019)
pubimg

The ongoing migration of HMDs to the consumer market also allows the integration of immersive environments into analysis workflows that are often bound to an (office) desk. However, a critical factor when considering VR solutions for professional applications is the prevention of cybersickness. In the given scenario the user is usually seated and the surrounding real world environment is very dominant, where the most dominant part is maybe the desk itself. Including this desk in the virtual environment could serve as a resting frame and thus reduce cybersickness next to a lot of further possibilities. In this work, we evaluate the feasibility of a substitution like this in the context of a visual data analysis task involving travel, and measure the impact on cybersickness as well as the general task performance and presence. In the conducted user study (n=52), surprisingly, and partially in contradiction to existing work, we found no significant differences for those core measures between the control condition without a virtual table and the condition containing a virtual table. However, the results also support the inclusion of a virtual table in desk-based use cases.

» Show BibTeX

@inproceedings{zielasko2019travel,
title={{A Non-Stationary Office Desk Substitution for Desk-Based and HMD-Projected Virtual Reality}},
author={Zielasko, Daniel and Weyers, Benjamin and Kuhlen, Torsten W},
booktitle ={Proc. of IEEE VR Workshop on Immersive Sickness Prevention},
year={2019}
}





Evaluation of Omnipresent Virtual Agents Embedded as Temporarily Required Assistants in Immersive Environments


Andrea Bönsch, Jan Hoffmann, Jonathan Wendt, Torsten Wolfgang Kuhlen
IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE), 2019
pubimg

When designing the behavior of embodied, computer-controlled, human-like virtual agents (VA) serving as temporarily required assistants in virtual reality applications, two linked factors have to be considered: the time the VA is visible in the scene, defined as presence time (PT), and the time till the VA is actually available for support on a user’s calling, defined as approaching time (AT).

Complementing a previous research on behaviors with a low VA’s PT, we present the results of a controlled within-subjects study investigating behaviors by which the VA is always visible, i.e., behaviors with a high PT. The two behaviors affecting the AT tested are: following, a design in which the VA is omnipresent and constantly follows the users, and busy, a design in which theVAis self-reliantly spending time nearby the users and approaches them only if explicitly asked for. The results indicate that subjects prefer the following VA, a behavior which also leads to slightly lower execution times compared to busy.

» Show Videos
» Show BibTeX

@InProceedings{Boensch2019c,
author = {Andrea B\"{o}nsch and Jan Hoffmann and Jonathan Wendt and Torsten W. Kuhlen},
title = {{Evaluation of Omnipresent Virtual Agents Embedded as Temporarily Required Assistants in Immersive Environments}},
booktitle = {IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE)},
year = {2019},
doi={10.1109/VHCIE.2019.8714726},
month={March}
}





An Empirical Lab Study Investigating If Higher Levels of Immersion Increase the Willingness to Donate


Andrea Bönsch, Alexander Kies, Moritz Jörling, Stefanie Paluch, Torsten Wolfgang Kuhlen
IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE), 2019
pubimg

Technological innovations have a growing relevance for charitable donations, as new technologies shape the way we perceive and approach digital media. In a between-subjects study with sixty-one volunteers, we investigated whether a higher degree of immersion for the potential donor can yield more donations for non-governmental organizations. Therefore, we compared the donations given after experiencing a video-based, an augmented-reality-based, or a virtual-reality-based scenery with a virtual agent, representing a war victimized Syrian boy talking about his losses. Our initial results indicate that the immersion has no impact. However, the donor’s perceived innovativeness of the used technology might be an influencing factor.

» Show Videos
» Show BibTeX

@InProceedings{Boensch2019b,
author = {Andrea B\"{o}nsch and Alexander Kies and Moritz Jörling and Stefanie Paluch and Torsten W. Kuhlen},
title = {{An Empirical Lab Study Investigating If Higher Levels of Immersion Increase the Willingness to Donatee}},
booktitle = {IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE)},
year = {2019}
pages={1-4},
doi={10.1109/VHCIE.2019.8714622},
month={March}
}





Toward Rigorous Parameterization of Underconstrained Neural Network Models Through Interactive Visualization and Steering of Connectivity Generation


Christian Nowke, Sandra Diaz-Pier, Benjamin Weyers, Bernd Hentschel, Abigail Morrison, Torsten Wolfgang Kuhlen, Alexander Peyser
Frontiers in Neuroinformatics 12, article 32
pubimg

Simulation models in many scientific fields can have non-unique solutions or unique solutions which can be difficult to find. Moreover, in evolving systems, unique ?nal state solutions can be reached by multiple different trajectories. Neuroscience is no exception. Often, neural network models are subject to parameter fitting to obtain desirable output comparable to experimental data. Parameter fitting without sufficient constraints and a systematic exploration of the possible solution space can lead to conclusions valid only around local minima or around non-minima. To address this issue, we have developed an interactive tool for visualizing and steering parameters in neural network simulation models. In this work, we focus particularly on connectivity generation, since ?nding suitable connectivity configurations for neural network models constitutes a complex parameter search scenario. The development of the tool has been guided by several use cases—the tool allows researchers to steer the parameters of the connectivity generation during the simulation, thus quickly growing networks composed of multiple populations with a targeted mean activity. The flexibility of the software allows scientists to explore other connectivity and neuron variables apart from the ones presented as use cases. With this tool, we enable an interactive exploration of parameter spaces and a better understanding of neural network models and grapple with the crucial problem of non-unique network solutions and trajectories. In addition, we observe a reduction in turn around times for the assessment of these models, due to interactive visualization while the simulation is computed.

» Show BibTeX

@ARTICLE{10.3389/fninf.2018.00032,

AUTHOR={Nowke, Christian and Diaz-Pier, Sandra and Weyers, Benjamin and Hentschel, Bernd and Morrison, Abigail and Kuhlen, Torsten W. and Peyser, Alexander},

TITLE={Toward Rigorous Parameterization of Underconstrained Neural Network Models Through Interactive Visualization and Steering of Connectivity Generation},

JOURNAL={Frontiers in Neuroinformatics},

VOLUME={12},

PAGES={32},

YEAR={2018},

URL={https://www.frontiersin.org/article/10.3389/fninf.2018.00032},

DOI={10.3389/fninf.2018.00032},

ISSN={1662-5196},

ABSTRACT={Simulation models in many scientific fields can have non-unique solutions or unique solutions which can be difficult to find.
Moreover, in evolving systems, unique final state solutions can be reached by multiple different trajectories.
Neuroscience is no exception. Often, neural network models are subject to parameter fitting to obtain desirable output comparable to experimental data. Parameter fitting without sufficient constraints and a systematic exploration of the possible solution space can lead to conclusions valid only around local minima or around non-minima. To address this issue, we have developed an interactive tool for visualizing and steering parameters in neural network simulation models.
In this work, we focus particularly on connectivity generation, since finding suitable connectivity configurations for neural network models constitutes a complex parameter search scenario. The development of the tool has been guided by several use cases -- the tool allows researchers to steer the parameters of the connectivity generation during the simulation, thus quickly growing networks composed of multiple populations with a targeted mean activity. The flexibility of the software allows scientists to explore other connectivity and neuron variables apart from the ones presented as use cases. With this tool, we enable an interactive exploration of parameter spaces and a better understanding of neural network models and grapple with the crucial problem of non-unique network solutions and trajectories. In addition, we observe a reduction in turn around times for the assessment of these models, due to interactive visualization while the simulation is computed.}
}





VIOLA : a Multi-Purpose and Web-Based Visualization Tool for Neuronal-Network Simulation Output


Johanna Senk, Corto Carde, Espen Hagen, Torsten Wolfgang Kuhlen, Markus Diesmann, Benjamin Weyers
Frontiers in Neuroinformatics 12, article 75
pubimg

Neuronal network models and corresponding computer simulations are invaluable tools to aid the interpretation of the relationship between neuron properties, connectivity, and measured activity in cortical tissue. Spatiotemporal patterns of activity propagating across the cortical surface as observed experimentally can for example be described by neuronal network models with layered geometry and distance-dependent connectivity. In order to cover the surface area captured by today’s experimental techniques and to achieve sufficient self-consistency, such models contain millions of nerve cells. The interpretation of the resulting stream of multi-modal and multi-dimensional simulation data calls for integrating interactive visualization steps into existing simulation-analysis workflows. Here, we present a set of interactive visualization concepts called views for the visual analysis of activity data in topological network models, and a corresponding reference implementation VIOLA (VIsualization Of Layer Activity). The software is a lightweight, open-source, web-based, and platform-independent application combining and adapting modern interactive visualization paradigms, such as coordinated multiple views, for massively parallel neurophysiological data. For a use-case demonstration we consider spiking activity data of a two-population, layered point-neuron network model incorporating distance-dependent connectivity subject to a spatially confined excitation originating from an external population. With the multiple coordinated views, an explorative and qualitative assessment of the spatiotemporal features of neuronal activity can be performed upfront of a detailed quantitative data analysis of speci?c aspects of the data. Interactive multi-view analysis therefore assists existing data Analysis workflows. Furthermore,ongoingeffortsincludingtheEuropeanHumanBrainProjectaim at providing online user portals for integrated model development, simulation, analysis, and provenance tracking, wherein interactive visual analysis tools are one component. Browser-compatible, web-technology based solutions are therefore required. Within this scope, with VIOLA we provide a first prototype.

» Show BibTeX

@ARTICLE{10.3389/fninf.2018.00075,

AUTHOR={Senk, Johanna and Carde, Corto and Hagen, Espen and Kuhlen, Torsten W. and Diesmann, Markus and Weyers, Benjamin},

TITLE={VIOLA—A Multi-Purpose and Web-Based Visualization Tool for Neuronal-Network Simulation Output},

JOURNAL={Frontiers in Neuroinformatics},

VOLUME={12},

PAGES={75},

YEAR={2018},

URL={https://www.frontiersin.org/article/10.3389/fninf.2018.00075},

DOI={10.3389/fninf.2018.00075},

ISSN={1662-5196},

ABSTRACT={Neuronal network models and corresponding computer simulations are invaluable tools to aid the interpretation of the relationship between neuron properties, connectivity and measured activity in cortical tissue. Spatiotemporal patterns of activity propagating across the cortical surface as observed experimentally can for example be described by neuronal network models with layered geometry and distance-dependent connectivity. In order to cover the surface area captured by today's experimental techniques and to achieve sufficient self-consistency, such models contain millions of nerve cells. The interpretation of the resulting stream of multi-modal and multi-dimensional simulation data calls for integrating interactive visualization steps into existing simulation-analysis workflows. Here, we present a set of interactive visualization concepts called views for the visual analysis of activity data in topological network models, and a corresponding reference implementation VIOLA (VIsualization Of Layer Activity). The software is a lightweight, open-source, web-based and platform-independent application combining and adapting modern interactive visualization paradigms, such as coordinated multiple views, for massively parallel neurophysiological data. For a use-case demonstration we consider spiking activity data of a two-population, layered point-neuron network model incorporating distance-dependent connectivity subject to a spatially confined excitation originating from an external population. With the multiple coordinated views, an explorative and qualitative assessment of the spatiotemporal features of neuronal activity can be performed upfront of a detailed quantitative data analysis of specific aspects of the data. Interactive multi-view analysis therefore assists existing data analysis workflows. Furthermore, ongoing efforts including the European Human Brain Project aim at providing online user portals for integrated model development, simulation, analysis and provenance tracking, wherein interactive visual analysis tools are one component. Browser-compatible, web-technology based solutions are therefore required. Within this scope, with VIOLA we provide a first prototype.}
}





Immersive Analytics Applications in Life and Health Sciences


Tobias Czauderna, Jason Haga, Jinman Kim, Matthias Klapperstueck, Karsten Klein, Torsten Wolfgang Kuhlen, Steffen Oeltze-Jafra, Bjoern Sommer, Falk Schreiber
In Kim Marriott, Falk Schreiber et al. (eds.): Immersive Analytics, Springer International Publishing, pp. 289-330.
pubimg

Life and health sciences are key application areas for immersive analytics. This spans a broad range including medicine (e.g., investigations in tumour boards), pharmacology (e.g., research of adverse drug reactions), biology (e.g., immersive virtual cells) and ecology (e.g., analytics of animal behaviour). We present a brief overview of general applications of immersive analytics in the life and health sciences, and present a number of applications in detail, such as immersive analytics in structural biology, in medical image analytics, in neurosciences, in epidemiology, in biological network analysis and for virtual cells.

» Show BibTeX

@Inbook{Czauderna2018,
author="Czauderna, Tobias
and Haga, Jason
and Kim, Jinman
and Klapperst{\"u}ck, Matthias
and Klein, Karsten
and Kuhlen, Torsten
and Oeltze-Jafra, Steffen
and Sommer, Bj{\"o}rn
and Schreiber, Falk",
editor="Marriott, Kim
and Schreiber, Falk
and Dwyer, Tim
and Klein, Karsten
and Riche, Nathalie Henry
and Itoh, Takayuki
and Stuerzlinger, Wolfgang
and Thomas, Bruce H.",
title="Immersive Analytics Applications in Life and Health Sciences",
bookTitle="Immersive Analytics",
year="2018",
publisher="Springer International Publishing",
address="Cham",
pages="289--330",
abstract="Life and health sciences are key application areas for immersive analytics. This spans a broad range including medicine (e.g., investigations in tumour boards), pharmacology (e.g., research of adverse drug reactions), biology (e.g., immersive virtual cells) and ecology (e.g., analytics of animal behaviour). We present a brief overview of general applications of immersive analytics in the life and health sciences, and present a number of applications in detail, such as immersive analytics in structural biology, in medical image analytics, in neurosciences, in epidemiology, in biological network analysis and for virtual cells.",
isbn="978-3-030-01388-2",
doi="10.1007/978-3-030-01388-2_10",
url="https://doi.org/10.1007/978-3-030-01388-2_10"
}





Feature Tracking by Two-Step Optimization


Andrea Schnorr, Dirk Norbert Helmrich, Dominik Denker, Torsten Wolfgang Kuhlen, Bernd Hentschel
IEEE Transactions on Visualization and Computer Graphics (TVCG)
pubimg

Tracking the temporal evolution of features in time-varying data is a key method in visualization. For typical feature definitions, such as vortices, objects are sparsely distributed over the data domain. In this paper, we present a novel approach for tracking both sparse and space-filling features. While the former comprise only a small fraction of the domain, the latter form a set of objects whose union covers the domain entirely while the individual objects are mutually disjunct. Our approach determines the assignment of features between two successive time-steps by solving two graph optimization problems. It first resolves one-to-one assignments of features by computing a maximum-weight, maximum-cardinality matching on a weighted bi-partite graph. Second, our algorithm detects events by creating a graph of potentially conflicting event explanations and finding a weighted, independent set in it. We demonstrate our method's effectiveness on synthetic and simulation data sets, the former of which enables quantitative evaluation because of the availability of ground-truth information. Here, our method performs on par or better than a well-established reference algorithm. In addition, manual visual inspection by our collaborators confirm the results' plausibility for simulation data.

» Show BibTeX

@ARTICLE{Schnorr2018,
author = {Andrea Schnorr and Dirk N. Helmrich and Dominik Denker and Torsten W. Kuhlen and Bernd Hentschel},
title = {{F}eature {T}racking by {T}wo-{S}tep {O}ptimization},
journal = TVCG,
volume = {preprint available online},
doi = {https://doi.org/10.1109/TVCG.2018.2883630},
year = 2018,
}





Exploring Immersive Analytics for Built Environments


Tom Chandler, Thomas Morgan, Torsten Wolfgang Kuhlen
In Kim Marriott, Falk Schreiber et al. (eds.): Immersive Analytics, Springer International Publishing, pp. 331-357.
pubimg

This chapter overviews the application of immersive analytics to simulations of built environments through three distinct case studies. The first case study examines an immersive analytics approach based upon the concept of “Virtual Production Intelligence” for virtual prototyping tools throughout the planning phase of complete production sites. The second study addresses the 3D simulation of an extensive urban area and the attendant immersive analytic considerations in an interactive model of a sustainable city. The third study reviews how immersive analytic overlays have been applied for virtual heritage in the reconstruction and crowd simulation of the medieval Cambodian temple complex of Angkor Wat.

» Show BibTeX

@Inbook{Chandler2018,
author="Chandler, Tom
and Morgan, Thomas
and Kuhlen, Torsten Wolfgang",
editor="Marriott, Kim
and Schreiber, Falk
and Dwyer, Tim
and Klein, Karsten
and Riche, Nathalie Henry
and Itoh, Takayuki
and Stuerzlinger, Wolfgang
and Thomas, Bruce H.",
title="Exploring Immersive Analytics for Built Environments",
bookTitle="Immersive Analytics",
year="2018",
publisher="Springer International Publishing",
address="Cham",
pages="331--357",
abstract="This chapter overviews the application of immersive analytics to simulations of built environments through three distinct case studies. The first case study examines an immersive analytics approach based upon the concept of ``Virtual Production Intelligence'' for virtual prototyping tools throughout the planning phase of complete production sites. The second study addresses the 3D simulation of an extensive urban area (191 km{\$}{\$}^2{\$}{\$}) and the attendant immersive analytic considerations in an interactive model of a sustainable city. The third study reviews how immersive analytic overlays have been applied for virtual heritage in the reconstruction and crowd simulation of the medieval Cambodian temple complex of Angkor Wat.",
isbn="978-3-030-01388-2",
doi="10.1007/978-3-030-01388-2_11",
url="https://doi.org/10.1007/978-3-030-01388-2_11"
}





Interactive Visual Analysis of Multi-dimensional Metamodels


Sascha Gebhardt, Sebastian Pick, Bernd Hentschel, Torsten Wolfgang Kuhlen
Eurographics Symposium on Parallel Graphics and Visualization (EGPGV), Brno , Czech Republic
pubimg

In the simulation of manufacturing processes, complex models are used to examine process properties. To save computation time, so-called metamodels serve as surrogates for the original models. Metamodels are inherently difficult to interpret, because they resemble multi-dimensional functions f : Rn -> Rm that map configuration parameters to production criteria. We propose a multi-view visualization application called memoSlice that composes several visualization techniques, specially adapted to the analysis of metamodels. With our application, we enable users to improve their understanding of a metamodel, but also to easily optimize processes. We put special attention on providing a high level of interactivity by realizing specialized parallelization techniques to provide timely feedback on user interactions. In this paper we outline these parallelization techniques and demonstrate their effectivity by means of micro and high level measurements.

» Show BibTeX

@inproceedings {pgv.20181098,
booktitle = {Eurographics Symposium on Parallel Graphics and Visualization},
editor = {Hank Childs and Fernando Cucchietti},
title = {{Interactive Visual Analysis of Multi-dimensional Metamodels}},
author = {Gebhardt, Sascha and Pick, Sebastian and Hentschel, Bernd and Kuhlen, Torsten Wolfgang},
year = {2018},
publisher = {The Eurographics Association},
ISSN = {1727-348X},
ISBN = {978-3-03868-054-3},
DOI = {10.2312/pgv.20181098}
}





Social VR: How Personal Space is Affected by Virtual Agents’ Emotions


Andrea Bönsch, Sina Radke, Heiko Overath, Laura Marie Aschè, Jonathan Wendt, Tom Vierjahn, Ute Habel, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Conference on Virtual Reality and 3D User Interfaces (VR), 2018
pubimg

Personal space (PS), the flexible protective zone maintained around oneself, is a key element of everyday social interactions. It, e.g., affects people's interpersonal distance and is thus largely involved when navigating through social environments. However, the PS is regulated dynamically, its size depends on numerous social and personal characteristics and its violation evokes different levels of discomfort and physiological arousal. Thus, gaining more insight into this phenomenon is important.

We contribute to the PS investigations by presenting the results of a controlled experiment in a CAVE, focusing on German males in the age of 18 to 30 years. The PS preferences of 27 participants have been sampled while they were approached by either a single embodied, computer-controlled virtual agent (VA) or by a group of three VAs. In order to investigate the influence of a VA's emotions, we altered their facial expression between angry and happy. Our results indicate that the emotion as well as the number of VAs approaching influence the PS: larger distances are chosen to angry VAs compared to happy ones; single VAs are allowed closer compared to the group. Thus, our study is a foundation for social and behavioral studies investigating PS preferences.

» Show BibTeX

@InProceedings{Boensch2018c,
author = {Andrea B\"{o}nsch and Sina Radke and Heiko Overath and Laura M. Asch\'{e} and Jonathan Wendt and Tom Vierjahn and Ute Habel and Torsten W. Kuhlen},
title = {{Social VR: How Personal Space is Affected by Virtual Agents’ Emotions}},
booktitle = {Proceedings of the IEEE Conference on Virtual Reality and 3D User Interfaces (VR) 2018},
year = {2018}
}





Streaming Live Neuronal Simulation Data into Visualization and Analysis


Simon Oehrl, Jan Müller, Jan Schnathmeier, Jochen M. Eppler, Alexander Peyser, Hans Ekkehard Plesser, Benjamin Weyers, Bernd Hentschel, Torsten Wolfgang Kuhlen, Tom Vierjahn
ISC High Performance 2018
pubimg

Neuroscientists want to inspect the data their simulations are producing while these are still running. This will on the one hand save them time waiting for results and therefore insight. On the other, it will allow for more efficient use of CPU time if the simulations are being run on supercomputers. If they had access to the data being generated, neuroscientists could monitor it and take counter-actions, e.g., parameter adjustments, should the simulation deviate too much from in-vivo observations or get stuck.

As a first step toward this goal, we devise an in situ pipeline tailored to the neuroscientific use case. It is capable of recording and transferring simulation data to an analysis/visualization process, while the simulation is still running. The developed libraries are made publicly available as open source projects. We provide a proof-of-concept integration, coupling the neuronal simulator NEST to basic 2D and 3D visualization.

» Show BibTeX

@InProceedings{10.1007/978-3-030-02465-9_18,
author="Oehrl, Simon
and M{\"u}ller, Jan
and Schnathmeier, Jan
and Eppler, Jochen Martin
and Peyser, Alexander
and Plesser, Hans Ekkehard
and Weyers, Benjamin
and Hentschel, Bernd
and Kuhlen, Torsten W.
and Vierjahn, Tom",
editor="Yokota, Rio
and Weiland, Mich{\`e}le
and Shalf, John
and Alam, Sadaf",
title="Streaming Live Neuronal Simulation Data into Visualization and Analysis",
booktitle="High Performance Computing",
year="2018",
publisher="Springer International Publishing",
address="Cham",
pages="258--272",
abstract="Neuroscientists want to inspect the data their simulations are producing while these are still running. This will on the one hand save them time waiting for results and therefore insight. On the other, it will allow for more efficient use of CPU time if the simulations are being run on supercomputers. If they had access to the data being generated, neuroscientists could monitor it and take counter-actions, e.g., parameter adjustments, should the simulation deviate too much from in-vivo observations or get stuck.",
isbn="978-3-030-02465-9"
}





Interactive Exploration Assistance for Immersive Virtual Environments Based on Object Visibility and Viewpoint Quality


Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference 2018
pubimg

During free exploration of an unknown virtual scene, users often miss important parts, leading to incorrect or incomplete environment knowledge and a potential negative impact on performance in later tasks. This is addressed by wayfinding aids such as compasses, maps, or trails, and automated exploration schemes such as guided tours. However, these approaches either do not actually ensure exploration success or take away control from the user.

Therefore, we present an interactive assistance interface to support exploration that guides users to interesting and unvisited parts of the scene upon request, supplementing their own, free exploration. It is based on an automated analysis of object visibility and viewpoint quality and is therefore applicable to a wide range of scenes without human supervision or manual input. In a user study, we found that the approach improves users' knowledge of the environment, leads to a more complete exploration of the scene, and is also subjectively helpful and easy to use.

» Show Videos



Does the Directivity of a Virtual Agent’s Speech Influence the Perceived Social Presence?


Jonathan Wendt, Benjamin Weyers, Andrea Bönsch, Jonas Stienen, Tom Vierjahn, Michael Vorländer, Torsten Wolfgang Kuhlen
IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE), 2018
pubimg

When interacting and communicating with virtual agents in immersive environments, the agents’ behavior should be believable and authentic. Thereby, one important aspect is a convincing auralizations of their speech. In this work-in progress paper a study design to evaluate the effect of adding directivity to speech sound source on the perceived social presence of a virtual agent is presented. Therefore, we describe the study design and discuss first results of a prestudy as well as consequential improvements of the design.


» Show Videos
» Show BibTeX

@InProceedings{Boensch2018b,
author = {Jonathan Wendt and Benjamin Weyers and Andrea B\"{o}nsch and Jonas Stienen and Tom Vierjahn and Michael Vorländer and Torsten W. Kuhlen },
title = {{Does the Directivity of a Virtual Agent’s Speech Influence the Perceived Social Presence?}},
booktitle = {IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE)},
year = {2018}
}





Dynamic Field of View Reduction Related to Subjective Sickness Measures in an HMD-based Data Analysis Task


Daniel Zielasko, Alexander Meißner, Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
IEEE Virtual Reality Workshop on Everyday Virtual Reality 2018
pubimg

Various factors influence the degree of cybersickness a user can suffer in an immersive virtual environment, some of which can be controlled without adapting the virtual environment itself. When using HMDs, one example is the size of the field of view. However, the degree to which factors like this can be manipulated without affecting the user negatively in other ways is limited. Another prominent characteristic of cybersickness is that it affects individuals very differently. Therefore, to account for both the possible disruptive nature of alleviating factors and the high interpersonal variance, a promising approach may be to intervene only in cases where users experience discomfort symptoms, and only as much as necessary. Thus, we conducted a first experiment, where the field of view was decreased when people feel uncomfortable, to evaluate the possible positive impact on sickness and negative influence on presence. While we found no significant evidence for any of these possible effects, interesting further results and observations were made.

» Show Videos
» Show BibTeX

@InProceedings{zielasko2018,
title={{Dynamic Field of View Reduction Related to Subjective Sickness Measures in an HMD-based Data Analysis Task}},
author={Zielasko, Daniel and Mei{\ss}ner, Alexander and Freitag Sebastian and Weyers, Benjamin and Kuhlen, Torsten W},
booktitle ={Proc. of IEEE Virtual Reality Workshop on Everyday Virtual Reality},
year={2018}
}





Towards Understanding the Influence of a Virtual Agent’s Emotional Expression on Personal Space


Andrea Bönsch, Sina Radke, Jonathan Wendt, Tom Vierjahn, Ute Habel, Torsten Wolfgang Kuhlen
IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE), 2018
pubimg

The concept of personal space is a key element of social interactions. As such, it is a recurring subject of investigations in the context of research on proxemics. Using virtual-reality-based experiments, we contribute to this area by evaluating the direct effects of emotional expressions of an approaching virtual agent on an individual’s behavioral and physiological responses. As a pilot study focusing on the emotion expressed solely by facial expressions gave promising results, we now present a study design to gain more insight.

» Show BibTeX

@InProceedings{Boensch2018b,
author = {Andrea B\"{o}nsch and Sina Radke and Jonathan Wendt and Tom Vierjahn and Ute Habel and Torsten W. Kuhlen},
title = {{Towards Understanding the Influence of a Virtual Agent’s Emotional Expression on Personal Space}},
booktitle = {IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE)},
year = {2018}
}





Fluid Sketching — Immersive Sketching Based on Fluid Flow


Sevinc Eroglu, Sascha Gebhardt, Patric Schmitz, Dominik Rausch, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality 2018
pubimg

Fluid artwork refers to works of art based on the aesthetics of fluid motion, such as smoke photography, ink injection into water, and paper marbling. Inspired by such types of art, we created Fluid Sketching as a novel medium for creating 3D fluid artwork in immersive virtual environments. It allows artists to draw 3D fluid-like sketches and manipulate them via six degrees of freedom input devices. Different sets of brush strokes are available, varying different characteristics of the fluid. Because of fluid's nature, the diffusion of the drawn fluid sketch is animated, and artists have control over altering the fluid properties and stopping the diffusion process whenever they are satisfied with the current result. Furthermore, they can shape the drawn sketch by directly interacting with it, either with their hand or by blowing into the fluid. We rely on particle advection via curl-noise as a fast procedural method for animating the fluid flow.

» Show Videos
» Show BibTeX

@InProceedings{Eroglu2018,
author = {Eroglu, Sevinc and Gebhardt, Sascha and Schmitz, Patric and Rausch, Dominik and Kuhlen, Torsten Wolfgang},
title = {{Fluid Sketching — Immersive Sketching Based on Fluid Flow}},
booktitle = {Proceedings of IEEE Virtual Reality Conference 2018},
year = {2018}
}





Seamless Hand-Based Remote and Close Range Interaction in IVEs


Daniel Zielasko, Uta Skorzinski, Torsten Wolfgang Kuhlen, Benjamin Weyers
Mensch und Computer Workshop on Virtual and Augmented Reality in Everyday Context (2018)
pubimg

In this work, we describe a hybrid, hand-based interaction metaphor that makes remote and close objects in an HMD-based immersive virtual environment (IVE) seamlessly accessible. To accomplish this, different existing techniques, such as go-go and HOMER, were combined in a way that aims for generality, intuitiveness, uniformity, and speed. A technique like this is one prerequisite for a successful integration of IVEs to professional everyday applications, such as data analysis workflows.




Talk: Streaming Live Neuronal Simulation Data into Visualization and Analysis


Simon Oehrl, Jan Müller, Jan Schnathmeier, Benjamin Weyers, Jochen M. Eppler, Alexander Peyser, Hans Ekkehard Plesser, Bernd Hentschel, Torsten Wolfgang Kuhlen, Tom Vierjahn
NEST Conference 2018
pubimg

Being able to inspect neuronal network simulations while they are running provides new research strategies to neuroscientists as it enables them to perform actions like parameter adjustments in case the simulation performs unexpectedly. This can also save compute resources when such simulations are run on large supercomputers as errors can be detected and corrected earlier saving valuable compute time. This talk presents a prototypical pipeline that enables in-situ analysis and visualization of running simulations.




Fluid Sketching: Bringing Ebru Art into VR


Sevinc Eroglu, Benjamin Weyers, Torsten Wolfgang Kuhlen
Mensch und Computer 2018 - Workshopband
pubimg

In this interactive demo, we present our Fluid Sketching application as an innovative virtual reality-based interpretation of traditional marbling art. By using a particle-based simulation combined with natural, spatial, and multi-modal interaction techniques, we create and extend the original artistic work to build a comprehensive interactive experience. With the interactive demo of Fluid Sketching during Mensch und Computer 2018, we aim at increasing the awareness of paper marbling as traditional type of art and demonstrating the potential of virtual reality as new and innovative digital and artistic medium.

» Show BibTeX

@article{eroglu2018fluid,
title={Fluid Sketching: Bringing Ebru Art into VR},
author={Eroglu, Sevinc and Weyers, Benjamin and Kuhlen, Torsten},
journal={Mensch und Computer 2018-Workshopband},
year={2018},
publisher={Gesellschaft f{\"u}r Informatik eV}
}





Talk: Influence of Emotions on Personal Space Preferences


Andrea Bönsch, Sina Radke, Heiko Overath, Laura Marie Aschè, Jonathan Wendt, Tom Vierjahn, Ute Habel, Torsten Wolfgang Kuhlen
Virtual Environments: Current Topics in Psychological Research (VECTOR) workshop, 2018

Personal Space (PS) is regulated dynamically by choosing an appropriate interpersonal distance when navigating through social environments. This key element in social interactions is influenced by numerous social and personal characteristics, e.g., the nature of the relationship between the interaction partners and the other’s sex and age. Moreover, affective contexts and expressions of interaction partners influence PS preferences, evident, e.g., in larger distances to others in threatening situations or when confronted with angry-looking individuals. Given the prominent role of emotional expressions in our everyday social interactions, we investigate how emotions affect PS adaptions.




Interactive Exploration of Dissipation Element Geometry


Tom Vierjahn, Andrea Schnorr, Benjamin Weyers, Dominik Denker, Ingo Wald, Christoph Garth, Torsten Wolfgang Kuhlen, Bernd Hentschel
Eurographics Symposium on Parallel Graphics and Visualization (2017)
pubimg

Dissipation elements (DE) define a geometrical structure for the analysis of small-scale turbulence. Existing analyses based on DEs focus on a statistical treatment of large populations of DEs. In this paper, we propose a method for the interactive visualization of the geometrical shape of DE populations. We follow a two-step approach: in a pre-processing step, we approximate individual DEs by tube-like, implicit shapes with elliptical cross sections of varying radii; we then render these approximations by direct ray-casting thereby avoiding the need for costly generation of detailed, explicit geometry for rasterization. Our results demonstrate that the approximation gives a reasonable representation of DE geometries and the rendering performance is suitable for interactive use.

» Show BibTeX

@InProceedings{Vierjahn2017,
booktitle = {Eurographics Symposium on Parallel Graphics and Visualization},
author = {Tom Vierjahn and Andrea Schnorr and Benjamin Weyers and Dominik Denker and Ingo Wald and Christoph Garth and Torsten W. Kuhlen and Bernd Hentschel},
title = {Interactive Exploration of Dissipation Element Geometry},
year = {2017},
pages = {53--62},
ISSN = {1727-348X},
ISBN = {978-3-03868-034-5},
doi = {10.2312/pgv.20171093},
}





Measuring Insight into Multi-dimensional Data from a Combination of a Scatterplot Matrix and a HyperSlice Visualization


André Calero Valdez, Sascha Gebhardt, Torsten Wolfgang Kuhlen, Martina Ziefle
International Conference on Digital Human Modeling and Applications in Health, Safety, Ergonomics and Risk Management 2017
pubimg

Understanding multi-dimensional data and in particular multi-dimensional dependencies is hard. Information visualization can help to understand this type of data. Still, the problem of how users gain insights from such visualizations is not well understood. Both the visualizations and the users play a role in understanding the data. In a case study, using both, a scatterplot matrix and a HyperSlice with six-dimensional data, we asked 16 participants to think aloud and measured insights during the process of analyzing the data. The amount of insights was strongly correlated with spatial abilities. Interestingly, all users were able to complete an optimization task independently of self-reported understanding of the data.

» Show BibTeX

@Inbook{CaleroValdez2017,
author="Calero Valdez, Andr{\'e}
and Gebhardt, Sascha
and Kuhlen, Torsten W.
and Ziefle, Martina",
editor="Duffy, Vincent G.",
title="Measuring Insight into Multi-dimensional Data from a Combination of a Scatterplot Matrix and a HyperSlice Visualization",
bookTitle="Digital Human Modeling. Applications in Health, Safety, Ergonomics, and Risk Management: Health and Safety: 8th International Conference, DHM 2017, Held as Part of HCI International 2017, Vancouver, BC, Canada, July 9-14, 2017, Proceedings, Part II",
year="2017",
publisher="Springer International Publishing",
address="Cham",
pages="225--236",
isbn="978-3-319-58466-9",
doi="10.1007/978-3-319-58466-9_21",
url="http://dx.doi.org/10.1007/978-3-319-58466-9_21"
}





Interactive Level-of-Detail Visualization of 3D-Polarized Light Imaging Data Using Spherical Harmonics


Claudia Hänel, Ali Can Demiralp, Markus Axer, David Gräßel, Bernd Hentschel, Torsten Wolfgang Kuhlen
19th EG/VGTC Conference on Visualization (EuroVis 2017)
pubimg

3D-Polarized Light Imaging (3D-PLI) provides data that enables an exploration of brain fibers at very high resolution. However, the visualization poses several challenges. Beside the huge data set sizes, users have to visually perceive the pure amount of information which might be, among other aspects, inhibited for inner structures because of occlusion by outer layers of the brain. We propose a clustering of fiber directions by means of spherical harmonics using a level-of-detail structure by which the user can interactively choose a clustering degree according to the zoom level or details required. Furthermore, the clustering method can be used for the automatic grouping of similar spherical harmonics automatically into one representative. An optional overlay with a direct vector visualization of the 3D-PLI data provides a better anatomical context.



Honorable Mention for Best Short Paper!

» Show BibTeX

@inproceedings {Haenel2017Interactive,
booktitle = {EuroVis 2017 - Short Papers},
editor = {Barbora Kozlikova and Tobias Schreck and Thomas Wischgoll},
title = {{Interactive Level-of-Detail Visualization of 3D-Polarized Light Imaging Data Using Spherical Harmonics}},
author = {H\”anel, Claudia and Demiralp, Ali C. and Axer, Markus and Gr\”assel, David and Hentschel, Bernd and Kuhlen, Torsten W.},
year = {2017},
publisher = {The Eurographics Association},
ISBN = {978-3-03868-043-7},
DOI = {10.2312/eurovisshort.20171145}
}





Comparison of a speech-based and a pie-menu-based interaction metaphor for application control


Sebastian Pick, Andrew S. Puika, Torsten Wolfgang Kuhlen
In 2017 IEEE Virtual Reality (VR) Poster Proceedings

Choosing an adequate system control technique is crucial to support complex interaction scenarios in virtual reality applications. In this work, we compare an existing hierarchical pie-menu-based approach with a speech-recognition-based one in terms of task performance and user experience in a formal user study. As testbed, we use a factory planning application featuring a large set of system control options.

» Show BibTeX

@INPROCEEDINGS{Pick:691795,
author = {Pick, Sebastian and Puika, Andrew S. and Kuhlen, Torsten},
title = {{C}omparison of a speech-based and a pie-menu-based
interaction metaphor for application control},
address = {Piscataway, NJ},
publisher = {IEEE},
reportid = {RWTH-2017-06169},
pages = {381-382},
year = {2017},
comment = {2017 IEEE Virtual Reality (VR) : proceedings : March 18-22,
2017, Los Angeles, CA, USA / Evan Suma Rosenberg, David M.
Krum, Zachary Wartell, Betty Mohler, Sabarish V. Babu, Frank
Steinicke, and Victoria Interrante ; sponsored by IEEE
Computer Society, Visialization and Graphics Technical
Committee},
booktitle = {2017 IEEE Virtual Reality (VR) :
proceedings : March 18-22, 2017, Los
Angeles, CA, USA / Evan Suma Rosenberg,
David M. Krum, Zachary Wartell, Betty
Mohler, Sabarish V. Babu, Frank
Steinicke, and Victoria Interrante ;
sponsored by IEEE Computer Society,
Visialization and Graphics Technical
Committee},
month = {Mar},
date = {2017-03-18},
organization = {2017 IEEE Virtual Reality, Los
Angeles, CA (USA), 18 Mar 2017 - 22 Mar
2017},
cin = {124620 / 120000 / 080025},
cid = {$I:(DE-82)124620_20151124$ / $I:(DE-82)120000_20140620$ /
$I:(DE-82)080025_20140620$},
pnm = {B-1 - Virtual Production Intelligence},
pid = {G:(DE-82)X080025-B-1},
typ = {PUB:(DE-HGF)7 / PUB:(DE-HGF)8},
UT = {WOS:000403149400114},
doi = {10.1109/VR.2017.7892336},
url = {http://publications.rwth-aachen.de/record/691795},
}





buenoSDIAs: Supporting Desktop Immersive Analytics While Actively Preventing Cybersickness


Daniel Zielasko, Martin Bellgardt, Alexander Meißner, Maliheh Haghgoo, Bernd Hentschel, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of IEEE VIS Workshop on Immersive Analytics (2017)
pubimg

Immersive data analytics as an emerging research topic in scientific and information visualization has recently been brought back into the focus due to the emergence of low-cost consumer virtual reality hardware. Previous research has shown the positive impact of immersive visualization on data analytics workflows, but in most cases, insights were based on large-screen setups. In contrast, less research focuses on a close integration of immersive technology into existing, i.e., desktop-based data analytics workflows. This implies specific requirements regarding the usability of such systems, which include, i.e., the prevention of cybersickness. In this work, we present a prototypical application, which offers a first set of tools and addresses major challenges for a fully immersive data analytics setting in which the user is sitting at a desktop. In particular, we address the problem of cybersickness by integrating prevention strategies combined with individualized user profiles to maximize time of use.



Utilizing Immersive Virtual Reality in Everyday Work


Martin Bellgardt, Sebastian Pick, Daniel Zielasko, Tom Vierjahn, Benjamin Weyers, Torsten Wolfgang Kuhlen
Workshop on Everyday Virtual Reality (WEVR)
pubimg

Applications of Virtual Reality (VR) have been repeatedly explored with the goal to improve the data analysis process of users from different application domains, such as architecture and simulation sciences. Unfortunately, making VR available in professional application scenarios or even using it on a regular basis has proven to be challenging. We argue that everyday usage environments, such as office spaces, have introduced constraints that critically affect the design of interaction concepts since well-established techniques might be difficult to use. In our opinion, it is crucial to understand the impact of usage scenarios on interaction design, to successfully develop VR applications for everyday use. To substantiate our claim, we define three distinct usage scenarios in this work that primarily differ in the amount of mobility they allow for. We outline each scenario's inherent constraints but also point out opportunities that may be used to design novel, well-suited interaction techniques for different everyday usage environments. In addition, we link each scenario to a concrete application example to clarify its relevance and show how it affects interaction design.




Efficient Approximate Computation of Scene Visibility Based on Navigation Meshes and Applications for Navigation and Scene Analysis


Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Symposium on 3D User Interfaces (2017)
pubimg

Scene visibility - the information of which parts of the scene are visible from a certain location—can be used to derive various properties of a virtual environment. For example, it enables the computation of viewpoint quality to determine the informativeness of a viewpoint, helps in constructing virtual tours, and allows to keep track of the objects a user may already have seen. However, computing visibility at runtime may be too computationally expensive for many applications, while sampling the entire scene beforehand introduces a costly precomputation step and may include many samples not needed later on.

Therefore, in this paper, we propose a novel approach to precompute visibility information based on navigation meshes, a polygonal representation of a scene’s navigable areas. We show that with only limited precomputation, high accuracy can be achieved in these areas. Furthermore, we demonstrate the usefulness of the approach by means of several applications, including viewpoint quality computation, landmark and room detection, and exploration assistance. In addition, we present a travel interface based on common visibility that we found to result in less cybersickness in a user study.

» Show Videos
» Show BibTeX

@INPROCEEDINGS{freitag2017a,
author={Sebastian Freitag and Benjamin Weyers and Torsten W. Kuhlen},
booktitle={2017 IEEE Symposium on 3D User Interfaces (3DUI)},
title={{Efficient Approximate Computation of Scene Visibility Based on Navigation Meshes and Applications for Navigation and Scene Analysis}},
year={2017},
pages={134--143},
}





Approximating Optimal Sets of Views in Virtual Scenes


Sebastian Freitag, Clemens Löbbert, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference 2017
pubimg

Viewpoint quality estimation methods allow the determination of the most informative position in a scene. However, a single position usually cannot represent an entire scene, requiring instead a set of several viewpoints. Measuring the quality of such a set of views, however, is not trivial, and the computation of an optimal set of views is an NP-hard problem. Therefore, in this work, we propose three methods to estimate the quality of a set of views. Furthermore, we evaluate three approaches for computing an approximation to the optimal set (two of them new) regarding effectiveness and efficiency.




Assisted Travel Based on Common Visibility and Navigation Meshes


Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference 2017
pubimg

The manual adjustment of travel speed to cover medium or large distances in virtual environments may increase cognitive load, and manual travel at high speeds can lead to cybersickness due to inaccurate steering. In this work, we present an approach to quickly pass regions where the environment does not change much, using automated suggestions based on the computation of common visibility. In a user study, we show that our method can reduce cybersickness when compared with manual speed control.




BlowClick 2.0: A Trigger Based on Non-Verbal Vocal Input


Daniel Zielasko, Neha Neha, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference (2017)

The use of non-verbal vocal input (NVVI) as a hand-free trigger approach has proven to be valuable in previous work [Zielasko2015]. Nevertheless, BlowClick's original detection method is vulnerable to false positives and, thus, is limited in its potential use, e.g., together with acoustic feedback for the trigger. Therefore, we extend the existing approach by adding common machine learning methods. We found that a support vector machine (SVM) with Gaussian kernel performs best for detecting blowing with at least the same latency and more precision as before. Furthermore, we added acoustic feedback to the NVVI trigger, which increases the user's confidence. To evaluate the advanced trigger technique, we conducted a user study (n=33). The results confirm that it is a reliable trigger; alone and as part of a hands-free point-and-click interface.




A Reliable Non-Verbal Vocal Input Metaphor for Clicking


Daniel Zielasko, Neha Neha, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Symposium on 3D User Interaction (3DUI) 2017
pubimg

We extended BlowClick, a NVVI metaphor for clicking, by adding machine learning methods to more reliably classify blowing events. We found a support vector machine with Gaussian kernel performing the best with at least the same latency and more precision than before. Furthermore, we added acoustic feedback to the NVVI trigger, which increases the user's confidence. With this extended technique we conducted a user study with 33 participants and could confirm that it is possible to use NVVI as a reliable trigger as part of a hands-free point-and-click interface.




Remain Seated: Towards Fully-Immersive Desktop VR


Daniel Zielasko, Benjamin Weyers, Martin Bellgardt, Sebastian Pick, Alexander Meißner, Tom Vierjahn, Torsten Wolfgang Kuhlen
IEEE Virtual Reality Workshop on Everyday Virtual Reality 2017
pubimg

In this work we describe the scenario of fully-immersive desktop VR, which serves the overall goal to seamlessly integrate with existing workflows and workplaces of data analysts and researchers, such that they can benefit from the gain in productivity when immersed in their data-spaces. Furthermore, we provide a literature review showing the status quo of techniques and methods available for realizing this scenario under the raised restrictions. Finally, we propose a concept of an analysis framework and the decisions made and the decisions still to be taken, to outline how the described scenario and the collected methods are feasible in a real use case.




Evaluation of Approaching-Strategies of Temporarily Required Virtual Assistants in Immersive Environments


Andrea Bönsch, Tom Vierjahn, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Symposium on 3D User Interfaces 2017
pubimg

Embodied, virtual agents provide users assistance in agent-based support systems. To this end, two closely linked factors have to be considered for the agents’ behavioral design: their presence time (PT), i.e., the time in which the agents are visible, and the approaching time (AT), i.e., the time span between the user’s calling for an agent and the agent’s actual availability.

This work focuses on human-like assistants that are embedded in immersive scenes but that are required only temporarily. To the best of our knowledge, guidelines for a suitable trade-off between PT and AT of these assistants do not yet exist. We address this gap by presenting the results of a controlled within-subjects study in a CAVE. While keeping a low PT so that the agent is not perceived as annoying, three strategies affecting the AT, namely fading, walking, and running, are evaluated by 40 subjects. The results indicate no clear preference for either behavior. Instead, the necessity of a better trade-off between a low AT and an agent’s realistic behavior is demonstrated.

» Show BibTeX

@InProceedings{Boensch2017b,
Title = {Evaluation of Approaching-Strategies of Temporarily Required Virtual Assistants in Immersive Environments},
Author = {Andrea B\"{o}nsch and Tom Vierjahn and Torsten W. Kuhlen},
Booktitle = {IEEE Symposium on 3D User Interfaces},
Year = {2017},
Pages = {69-72}
}





Gistualizer: An Immersive Glyph for Multidimensional Datapoints


Martin Bellgardt, Sascha Gebhardt, Bernd Hentschel, Torsten Wolfgang Kuhlen
Workshop on Immersive Analytics 2017
pubimg

Data from diverse workflows is often too complex for an adequate analysis without visualization. One kind of data are multi-dimensional datasets, which can be visualized via a wide array of techniques. For instance, glyphs can be used to visualize individual datapoints. However, glyphs need to be actively looked at to be comprehended. This work explores a novel approach towards visualizing a single datapoint, with the intention of increasing the user’s awareness of it while they are looking at something else. The basic concept is to represent this point by a scene that surrounds the user in an immersive virtual environment. This idea is based on the observation that humans can extract low-detailed information, the so-called gist, from a scene nearly instantly (equal or less 100ms). We aim at providing a first step towards answering the question whether enough information can be encoded in the gist of a scene to represent a point in multi-dimensional space and if this information is helpful to the user’s understanding of this space.

» Show BibTeX

@inproceedings{Bellgardt2017,
author = {Bellgardt, Martin and Gebhardt, Sascha and Hentschel, Bernd and Kuhlen, Torsten W.},
booktitle = {Workshop on Immersive Analytics},
title = {{Gistualizer: An Immersive Glyph for Multidimensional Datapoints}},
year = {2017}
}





Turning Anonymous Members of a Multiagent System into Individuals


Andrea Bönsch, Tom Vierjahn, Ari Shapiro, Torsten Wolfgang Kuhlen
IEEE Virtual Humans and Crowds for Immersive Environments (VHCIE), 2017
pubimg

It is increasingly common to embed embodied, human-like, virtual agents into immersive virtual environments for either of the two use cases: (1) populating architectural scenes as anonymous members of a crowd and (2) meeting or supporting users as individual, intelligent and conversational agents. However, the new trend towards intelligent cyber physical systems inherently combines both use cases. Thus, we argue for the necessity of multiagent systems consisting of anonymous and autonomous agents, who temporarily turn into intelligent individuals. Besides purely enlivening the scene, each agent can thus be engaged into a situation-dependent interaction by the user, e.g., into a conversation or a joint task. To this end, we devise components for an agent’s behavioral design modeling the transition between an anonymous and an individual agent when a user approaches.

» Show BibTeX

@InProceedings{Boensch2017c,
Title = {{Turning Anonymous Members of a Multiagent System into Individuals}},
Author = {Andrea B\"{o}nsch, Tom Vierjahn, Ari Shapiro and Torsten W. Kuhlen},
Booktitle = {IEEE Virtual Humans and Crowds for Immersive Environments},
Year = {2017},
Keywords = {Virtual Humans; Virtual Reality; Intelligent Agents; Mutliagent System},
DOI ={ 10.1109/VHCIE.2017.7935620}
Owner = {ab280112},
Timestamp = {2017.02.28}
}





Poster: Score-Based Recommendation for Efficiently Selecting Individual Virtual Agents in Multi-Agent Systems


Andrea Bönsch, Robert Trisnadi, Jonathan Wendt, Tom Vierjahn, Torsten Wolfgang Kuhlen
Proceedings of 23rd ACM Symposium on Virtual Reality Software and Technology (VRST) 2017
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Controlling user-agent-interactions by means of an external operator includes selecting the virtual interaction partners fast and faultlessly. However, especially in immersive scenes with a large number of potential partners, this task is non-trivial.

Thus, we present a score-based recommendation system supporting an operator in the selection task. Agents are recommended as potential partners based on two parameters: the user’s distance to the agents and the user’s gazing direction. An additional graphical user interface (GUI) provides elements for configuring the system and for applying actions to those agents which the operator has confirmed as interaction partners.

» Show BibTeX

@InProceedings{Boensch2017d,
Title = {Score-Based Recommendation for Efficiently Selecting Individual
Virtual Agents in Multi-Agent Systems},
Author = {Andrea Bönsch and Robert Trisnadi and Jonathan Wendt and Tom Vierjahn, and Torsten
W. Kuhlen},
Booktitle = {Proceedings of 23rd ACM
Symposium on Virtual Reality Software and Technology},
Year = {2017},
Pages = {tba},
DOI={10.1145/3139131.3141215}
}





Poster: Towards a Design Space Characterizing Workflows that Take Advantage of Immersive Visualization


Tom Vierjahn, Daniel Zielasko, Kees van Kooten, Peter Messmer, Bernd Hentschel, Torsten Wolfgang Kuhlen, Benjamin Weyers
Proceedings of IEEE Virtual Reality Conference 2017

Immersive visualization (IV) fosters the creation of mental images of a data set, a scene, a procedure, etc. We devise an initial version of a design space for categorizing workflows that take advantage of IV. From this categorization, specific requirements for seamlessly integrating IV can be derived. We validate the design space with three workflows emerging from our research projects.

» Show BibTeX

@InProceedings{Vierjahn2017,
Title = {Towards a Design Space Characterizing Workflows that Take Advantage of Immersive Visualization},
Author = {Tom Vierjahn and Daniel Zielasko and Kees van Kooten and Peter Messmer and Bernd Hentschel and Torsten W. Kuhlen and Benjamin Weyers},
Booktitle = {IEEE Virtual Reality Conference Poster Proceedings},
Year = {2017},
Pages = {329-330},
DOI={10.1109/VR.2017.7892310}
}





Poster: Peers At Work: Economic Real-Effort Experiments In The Presence of Virtual Co-Workers


Andrea Bönsch, Jonathan Wendt, Heiko Overath, Özgür Gürerk, Christine Harbring, Christian Grund, Thomas Kittsteiner, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference 2017
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Traditionally, experimental economics uses controlled and incentivized field and lab experiments to analyze economic behavior. However, investigating peer effects in the classic settings is challenging due to the reflection problem: Who is influencing whom?

To overcome this, we enlarge the methodological toolbox of these experiments by means of Virtual Reality. After introducing and validating a real-effort sorting task, we embed a virtual agent as peer of a human subject, who independently performs an identical sorting task. We conducted two experiments investigating (a) the subject’s productivity adjustment due to peer effects and (b) the incentive effects on competition. Our results indicate a great potential for Virtual-Reality-based economic experiments.

» Show BibTeX

@InProceedings{Boensch2017a,
Title = {Peers At Work: Economic Real-Effort Experiments In The Presence of Virtual Co-Workers},
Author = {Andrea B\"{o}nsch and Jonathan Wendt and Heiko Overath and Özgür Gürerk and Christine Harbring and Christian Grund and Thomas Kittsteiner and Torsten W. Kuhlen},
Booktitle = {IEEE Virtual Reality Conference Poster Proceedings},
Year = {2017},
Pages = {301-302},
DOI = {10.1109/VR.2017.7892296}
}





Virtual Production Intelligence


Sabina Jeschke, Achim Kampker, Torsten Wolfgang Kuhlen, Günther Schuh, Wolfgang Schulz , Toufik Al Khawli, Christian Büscher, Urs Eppelt, Sascha Gebhardt, Kai Kreisköther, Sebastian Pick, Rudolf Reinhard, Hasan Tercan, Hanno Voet
In Christian Brecher, Denis Özdemir (eds.): Integrative Production Technology : Theory and Applications, pp. 177-251
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The research area Virtual Production Intelligence (VPI) focuses on the integrated support of collaborative planning processes for production systems and products. The focus of the research is on processes for information processing in the design domains Factory and Machine. These processes provide the integration and interactive analysis of emerging, mostly heterogeneous planning information. The demonstrators (flapAssist, memoSlice und VPI platform) that are Information systems serve for the validation of the scientific approaches and aim to realize a continuous and consistent information management in terms of the Digital Factory. Central challenges are the semantic information integration (e.g., by means of metamodelling), the subsequent evaluation as well as the visualization of planning information (e.g., by means of Visual Analytics and Virtual Reality). All scientific and technical work is done within an interdisciplinary team composed of engineers, computer scientists and physicists.

» Show BibTeX

@BOOK{Brecher:683508,
key = {683508},
editor = {Brecher, Christian and Özdemir, Denis},
title = {{I}ntegrative {P}roduction {T}echnology : {T}heory and
{A}pplications},
address = {Cham},
publisher = {Springer International Publishing},
reportid = {RWTH-2017-01369},
isbn = {978-3-319-47451-9},
pages = {XXXIX, 1100 Seiten : Illustrationen},
year = {2017},
cin = {417310 / 080025},
cid = {$I:(DE-82)417310_20140620$ / $I:(DE-82)080025_20140620$},
typ = {PUB:(DE-HGF)3},
doi = {10.1007/978-3-319-47452-6},
url = {http://publications.rwth-aachen.de/record/683508},
}





Do Not Invade: A Virtual-Reality-Framework to Study Personal Space


Jan Schnathmeier, Heiko Overath, Sina Radke, Andrea Bönsch, Ute Habel, Torsten Wolfgang Kuhlen
Virtuelle und Erweiterte Realität, 14. Workshop der GI-Fachgruppe VR/AR (2017)

The bachelor thesis’ aim was to develop a framework allowing to design and conduct virtual-reality-based user studies gaining insight into the concept of personal space.

» Show BibTeX

@Article{Schnathmeier2017,
Title = {Do Not Invade: A Virtual-Reality-Framework to Study Personal Space},
Author = {Jan Schnathmeier and Heiko Overath and Sina Radke and Andrea B\"{o}nsch and Ute Habel and Torsten W. Kuhlen},
Journal = {{V}irtuelle und {E}rweiterte {R}ealit\"at, 14. {W}orkshop der {GI}-{F}achgruppe {VR}/{AR}},
Year = {2017},
Pages = {203-204},
ISBN = {978-3-8440-5606-8}
Publisher = {Shaker Verlag}
}





Accurate and adaptive contact modeling for multi-rate multi-point haptic rendering of static and deformable environments


Thomas Knott, Torsten Wolfgang Kuhlen
Computers & Graphics (Journal) (2016)
pubimg

Common approaches for the haptic rendering of complex scenarios employ multi-rate simulation schemes. Here, the collision queries or the simulation of a complex deformable object are often performed asynchronously at a lower frequency, while some kind of intermediate contact representation is used to simulate interactions at the haptic rate. However, this can produce artifacts in the haptic rendering when the contact situation quickly changes and the intermediate representation is not able to reflect the changes due to the lower update rate.

We address this problem utilizing a novel contact model. It facilitates the creation of contact representations that are accurate for a large range of motions and multiple simulation time-steps. We handle problematic geometrically convex contact regions using a local convex decomposition and special constraints for convex areas. We combine our accurate contact model with an implicit temporal integration scheme to create an intermediate mechanical contact representation, which reflects the dynamic behavior of the simulated objects. To maintain a haptic real time simulation, the size of the region modeled by the contact representation is automatically adapted to the complexity of the geometry in contact. Moreover, we propose a new iterative solving scheme for the involved constrained dynamics problems. We increase the robustness of our method using techniques from trust region-based optimization. Our approach can be combined with standard methods for the modeling of deformable objects or constraint-based approaches for the modeling of, for instance, friction or joints. We demonstrate its benefits with respect to the simulation accuracy and the quality of the rendered haptic forces in several scenarios with one or more haptic proxies.

» Show BibTeX

@Article{Knott201668,
Title = {Accurate and adaptive contact modeling for multi-rate multi-point haptic rendering of static and deformable environments },
Author = {Thomas C. Knott and Torsten W. Kuhlen},
Journal = {Computers \& Graphics },
Year = {2016},
Pages = {68 - 80},
Volume = {57},

Abstract = {Abstract Common approaches for the haptic rendering of complex scenarios employ multi-rate simulation schemes. Here, the collision queries or the simulation of a complex deformable object are often performed asynchronously at a lower frequency, while some kind of intermediate contact representation is used to simulate interactions at the haptic rate. However, this can produce artifacts in the haptic rendering when the contact situation quickly changes and the intermediate representation is not able to reflect the changes due to the lower update rate. We address this problem utilizing a novel contact model. It facilitates the creation of contact representations that are accurate for a large range of motions and multiple simulation time-steps. We handle problematic geometrically convex contact regions using a local convex decomposition and special constraints for convex areas. We combine our accurate contact model with an implicit temporal integration scheme to create an intermediate mechanical contact representation, which reflects the dynamic behavior of the simulated objects. To maintain a haptic real time simulation, the size of the region modeled by the contact representation is automatically adapted to the complexity of the geometry in contact. Moreover, we propose a new iterative solving scheme for the involved constrained dynamics problems. We increase the robustness of our method using techniques from trust region-based optimization. Our approach can be combined with standard methods for the modeling of deformable objects or constraint-based approaches for the modeling of, for instance, friction or joints. We demonstrate its benefits with respect to the simulation accuracy and the quality of the rendered haptic forces in several scenarios with one or more haptic proxies. },
Doi = {http://dx.doi.org/10.1016/j.cag.2016.03.007},
ISSN = {0097-8493},
Keywords = {Haptic rendering},
Url = {http://www.sciencedirect.com/science/article/pii/S0097849316300206}
}





Interactive 3D Force-Directed Edge Bundling


Daniel Zielasko, Benjamin Weyers, Bernd Hentschel, Torsten Wolfgang Kuhlen
Computer Graphics Forum (Journal) (2016)
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Interactive analysis of 3D relational data is challenging. A common way of representing such data are node-link diagrams as they support analysts in achieving a mental model of the data. However, naïve 3D depictions of complex graphs tend to be visually cluttered, even more than in a 2D layout. This makes graph exploration and data analysis less efficient. This problem can be addressed by edge bundling. We introduce a 3D cluster-based edge bundling algorithm that is inspired by the force-directed edge bundling (FDEB) algorithm [Holten2009] and fulfills the requirements to be embedded in an interactive framework for spatial data analysis. It is parallelized and scales with the size of the graph regarding the runtime. Furthermore, it maintains the edge’s model and thus supports rendering the graph in different structural styles. We demonstrate this with a graph originating from a simulation of the function of a macaque brain.




Visual Quality Adjustment for Volume Rendering in a Head-Tracked Virtual Environment


Claudia Hänel, Benjamin Weyers, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE Transactions on Visualization and Computer Graphics (Journal) (2016)
pubimg

To avoid simulator sickness and improve presence in immersive virtual environments (IVEs), high frame rates and low latency are required. In contrast, volume rendering applications typically strive for high visual quality that induces high computational load and, thus, leads to low frame rates. To evaluate this trade-off in IVEs, we conducted a controlled user study with 53 participants. Search and count tasks were performed in a CAVE with varying volume rendering conditions which are applied according to viewer position updates corresponding to head tracking. The results of our study indicate that participants preferred the rendering condition with continuous adjustment of the visual quality over an instantaneous adjustment which guaranteed for low latency and over no adjustment providing constant high visual quality but rather low frame rates. Within the continuous condition, the participants showed best task performance and felt less disturbed by effects of the visualization during movements. Our findings provide a good basis for further evaluations of how to accelerate volume rendering in IVEs according to user’s preferences.

» Show BibTeX

@article{Hanel2016,
author = { H{\"{a}}nel, Claudia and Weyers, Benjamin and Hentschel, Bernd and Kuhlen, Torsten W.},
doi = {10.1109/TVCG.2016.2518338},
issn = {10772626},
journal = {IEEE Transactions on Visualization and Computer Graphics},
number = {4},
pages = {1472--1481},
pmid = {26780811},
title = {{Visual Quality Adjustment for Volume Rendering in a Head-Tracked Virtual Environment}},
volume = {22},
year = {2016}
}





Examining Rotation Gain in CAVE-like Virtual Environments


Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
IEEE Transactions on Visualization and Computer Graphics (Journal) (2016)
pubimg

When moving through a tracked immersive virtual environment, it is sometimes useful to deviate from the normal one-to-one mapping of real to virtual motion. One option is the application of rotation gain, where the virtual rotation of a user around the vertical axis is amplified or reduced by a factor. Previous research in head-mounted display environments has shown that rotation gain can go unnoticed to a certain extent, which is exploited in redirected walking techniques. Furthermore, it can be used to increase the effective field of regard in projection systems. However, rotation gain has never been studied in CAVE systems, yet. In this work, we present an experiment with 87 participants examining the effects of rotation gain in a CAVE-like virtual environment. The results show no significant effects of rotation gain on simulator sickness, presence, or user performance in a cognitive task, but indicate that there is a negative influence on spatial knowledge especially for inexperienced users. In secondary results, we could confirm results of previous work and demonstrate that they also hold for CAVE environments, showing a negative correlation between simulator sickness and presence, cognitive performance and spatial knowledge, a positive correlation between presence and spatial knowledge, a mitigating influence of experience with 3D applications and previous CAVE exposure on simulator sickness, and a higher incidence of simulator sickness in women.

» Show BibTeX

@ARTICLE{freitag2016a,
author={S. Freitag and B. Weyers and T. W. Kuhlen},
journal={IEEE Transactions on Visualization and Computer Graphics},
title={{Examining Rotation Gain in CAVE-like Virtual Environments}},
year={2016},
volume={22},
number={4},
pages={1462-1471},
doi={10.1109/TVCG.2016.2518298},
ISSN={1077-2626},
month={April},
}





Design and Evaluation of Data Annotation Workflows for CAVE-like Virtual Environments


Sebastian Pick, Benjamin Weyers, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE Transactions on Visualization and Computer Graphics (Journal) (2016)
pubimg

Data annotation finds increasing use in Virtual Reality applications with the goal to support the data analysis process, such as architectural reviews. In this context, a variety of different annotation systems for application to immersive virtual environments have been presented. While many interesting interaction designs for the data annotation workflow have emerged from them, important details and evaluations are often omitted. In particular, we observe that the process of handling metadata to interactively create and manage complex annotations is often not covered in detail. In this paper, we strive to improve this situation by focusing on the design of data annotation workflows and their evaluation. We propose a workflow design that facilitates the most important annotation operations, i.e., annotation creation, review, and modification. Our workflow design is easily extensible in terms of supported annotation and metadata types as well as interaction techniques, which makes it suitable for a variety of application scenarios. To evaluate it, we have conducted a user study in a CAVE-like virtual environment in which we compared our design to two alternatives in terms of a realistic annotation creation task. Our design obtained good results in terms of task performance and user experience.

» Show Videos



Towards the Ultimate Display for Neuroscientific Data Analysis


Torsten Wolfgang Kuhlen, Bernd Hentschel
Brain-Inspired Computing. BrainComp 2015. Lecture Notes in Computer Science
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This article wants to give some impulses for a discussion about how an “ultimate” display should look like to support the Neuroscience community in an optimal way. In particular, we will have a look at immersive display technology. Since its hype in the early 90’s, immersive Virtual Reality has undoubtedly been adopted as a useful tool in a variety of application domains and has indeed proven its potential to support the process of scientific data analysis. Yet, it is still an open question whether or not such non-standard displays make sense in the context of neuroscientific data analysis. We argue that the potential of immersive displays is neither about the raw pixel count only, nor about other hardware-centric characteristics. Instead, we advocate the design of intuitive and powerful user interfaces for a direct interaction with the data, which support the multi-view paradigm in an efficient and flexible way, and – finally – provide interactive response times even for huge amounts of data and when dealing multiple datasets simultaneously.

» Show BibTeX

@InBook{Kuhlen2016,
Title = {Towards the Ultimate Display for Neuroscientific Data Analysis},
Author = {Kuhlen, Torsten Wolfgang and Hentschel, Bernd},
Editor = {Amunts, Katrin and Grandinetti, Lucio and Lippert, Thomas and Petkov, Nicolai},
Pages = {157--168},
Publisher = {Springer International Publishing},
Year = {2016},
Address = {Cham},
Booktitle = {Brain-Inspired Computing: Second International Workshop, BrainComp 2015, Cetraro, Italy, July 6-10, 2015, Revised Selected Papers},
Doi = {10.1007/978-3-319-50862-7_12},
ISBN = {978-3-319-50862-7},
Url = {http://dx.doi.org/10.1007/978-3-319-50862-7_12}
}





Human Factors in Information Visualization and Decision Support Systems


André Calero Valdez, Philipp Brauner, Martina Ziefle, Torsten Wolfgang Kuhlen, Michael Sedlmair
Mensch und Computer 2016

With the increase in data availability and data volume it becomes increasingly important to extract information and actionable knowledge from data. Information Visualization helps the user to understand data by utilizing vision as a relatively parallel input channel to the user’s mind. Decision Support systems on the other hand help users in making information actionable, by suggesting beneficial decisions and presenting them in context. Both fields share a common need for understanding the interface between the computer and the human. This makes human factors research critical for both fields. Understanding limitations of human perception, cognition and action, as well as their variance must be understood to fully leverage information visualization and decision support. This article reflects on research agendas for investigating human factors in the aforementioned fields.

» Show BibTeX

@inproceedings{Valdez2016,
author = {Valdez, André Calero AND Brauner, Philipp AND Ziefle, Martina AND Kuhlen, Torsten Wolfgang AND Sedlmair, Michael},
title = {Human Factors in Information Visualization and Decision Support Systems},
booktitle = {Mensch und Computer 2016 – Workshopband},
year = {2016},
editor = {Weyers, Benjamin AND Dittmar, Anke},
pages = {},
publisher = {Gesellschaft für Informatik e.V.},
address = {Aachen}
}





Towards Multi-user Provenance Tracking of Visual Analysis Workflows over Multiple Applications


Claudia Hänel, Mohammad Khatami, Torsten Wolfgang Kuhlen, Benjamin Weyers
Proceedings of EuroVis Workshop on Reproducibility, Verification, and Validation in Visualization (EuroRV3) (2016)
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Provenance tracking for visual analysis workflows is still a challenge as especially interaction and collaboration aspects are poorly covered in existing realizations. Therefore, we propose a first prototype addressing these issues based on the PROV model. Interactions in multiple applications by multiple users can be tracked by means of a web interface and, thus, allowing even for tracking of remote-located collaboration partners. In the end, we demonstrate the applicability based on two use cases and discuss some open issues not addressed by our implementation so far but that can be easily integrated into our architecture.

» Show BibTeX

@inproceedings {eurorv3.20161112,
booktitle = {EuroVis Workshop on Reproducibility, Verification, and Validation in Visualization (EuroRV3)},
editor = {Kai Lawonn and Mario Hlawitschka and Paul Rosenthal},
title = {{Towards Multi-user Provenance Tracking of Visual Analysis Workflows over Multiple Applications}},
author = { H{\"{a}}nel, Claudia and Khatami, Mohammad and Kuhlen, Torsten W. and Weyers, Benjamin},
year = {2016},
publisher = {The Eurographics Association},
ISSN = {-},
ISBN = {978-3-03868-017-8},
DOI = {10.2312/eurorv3.20161112}
}





A Lightweight Electrotactile Feedback Device to Improve Grasping in Immersive Virtual Environments


Johannes Hummel, Janki Dodiya, Laura Eckardt, Robin Wolff, Andreas Gerndt, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference (2016)
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An immersive virtual environment is the ideal platform for the planning and training of on-orbit servicing missions. In such kind of virtual assembly simulation, grasping virtual objects is one of the most common and natural interactions. In this paper, we present a novel, small and lightweight electrotactile feedback device, specifically designed for immersive virtual environments. We conducted a study to assess the feasibility and usability of our interaction device. Results show that electrotactile feedback improved the user’s grasping in our virtual on-orbit servicing scenario. The task completion time was significantly lower and the precision of the user’s interaction was higher.




Collision Avoidance in the Presence of a Virtual Agent in Small-Scale Virtual Environments


Andrea Bönsch, Benjamin Weyers, Jonathan Wendt, Sebastian Freitag, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Symposium on 3D User Interfaces (2016)
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Computer-controlled, human-like virtual agents (VAs), are often embedded into immersive virtual environments (IVEs) in order to enliven a scene or to assist users. Certain constraints need to be fulfilled, e.g., a collision avoidance strategy allowing users to maintain their personal space. Violating this flexible protective zone causes discomfort in real-world situations and in IVEs. However, no studies on collision avoidance for small-scale IVEs have been conducted yet.

Our goal is to close this gap by presenting the results of a controlled user study in a CAVE. 27 participants were immersed in a small-scale office with the task of reaching the office door. Their way was blocked either by a male or female VA, representing their co-worker. The VA showed different behavioral patterns regarding gaze and locomotion. Our results indicate that participants preferred collaborative collision avoidance: they expect the VA to step aside in order to get more space to pass while being willing to adapt their own walking paths.

Honorable Mention for Best Technote!

» Show Videos
» Show BibTeX

@InProceedings{Boensch2016a,
Title = {Collision Avoidance in the Presence of a Virtual Agent in Small-Scale Virtual Environments},
Author = {Andrea B\"{o}nsch and Benjamin Weyers and Jonathan Wendt and Sebastian Freitag and Torsten W. Kuhlen},
Booktitle = {IEEE Symposium on 3D User Interfaces},
Year = {2016},
Pages = {145-148},

Abstract = {Computer-controlled, human-like virtual agents (VAs), are often embedded into immersive virtual environments (IVEs) in order to enliven a scene or to assist users. Certain constraints need to be fulfilled, e.g., a collision avoidance strategy allowing users to maintain
their personal space. Violating this flexible protective zone causes discomfort in real-world situations and in IVEs. However, no studies on collision avoidance for small-scale IVEs have been conducted yet. Our goal is to close this gap by presenting the results of a controlled
user study in a CAVE. 27 participants were immersed in a small-scale office with the task of reaching the office door. Theirwaywas blocked either by a male or female VA, representing their co-worker. The VA showed different behavioral patterns regarding gaze and locomotion.
Our results indicate that participants preferred collaborative collision avoidance: they expect the VA to step aside in order to get more space to pass while being willing to adapt their own walking paths.}
}





Automatic Speed Adjustment for Travel through Immersive Virtual Environments based on Viewpoint Quality


Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Symposium on 3D User Interfaces (2016)
pubimg

When traveling virtually through large scenes, long distances and different detail densities render fixed movement speeds impractical. However, to manually adjust the travel speed, users have to control an additional parameter, which may be uncomfortable and requires cognitive effort. Although automatic speed adjustment techniques exist, many of them can be problematic in indoor scenes. Therefore, we propose to automatically adjust travel speed based on viewpoint quality, originally a measure of the informativeness of a viewpoint. In a user study, we show that our technique is easy to use, allowing users to reach targets faster and use less cognitive resources than when choosing their speed manually.

Best Technote!

» Show BibTeX

@INPROCEEDINGS{freitag2016b,
author={S. Freitag and B. Weyers and T. W. Kuhlen},
booktitle={2016 IEEE Symposium on 3D User Interfaces (3DUI)},
title={{Automatic Speed Adjustment for Travel through Immersive Virtual Environments based on Viewpoint Quality}},
year={2016},
pages={67-70},
doi={10.1109/3DUI.2016.7460033},
month={March},
}





SWIFTER: Design and Evaluation of a Speech-based Text Input Metaphor for Immersive Virtual Environments


Sebastian Pick, Andrew S. Puika, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Symposium on 3D User Interfaces (2016)
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Text input is an important part of the data annotation process, where text is used to capture ideas and comments. For text entry in immersive virtual environments, for which standard keyboards usually do not work, various approaches have been proposed. While these solutions have mostly proven effective, there still remain certain shortcomings making further investigations worthwhile. Motivated by recent research, we propose the speech-based multimodal text entry system SWIFTER, which strives for simplicity while maintaining good performance. In an initial user study, we compared our approach to smartphone-based text entry within a CAVE-like virtual environment. Results indicate that SWIFTER reaches an average input rate of 23.6 words per minute and is positively received by users in terms of user experience.




Evaluation of Hands-Free HMD-Based Navigation Techniques for Immersive Data Analysis


Daniel Zielasko, Sven Horn, Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Symposium on 3D User Interfaces (2016)
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To use the full potential of immersive data analysis when wearing a head-mounted display, users have to be able to navigate through the spatial data. We collected, developed and evaluated 5 different hands-free navigation methods that are usable while seated in the analyst’s usual workplace. All methods meet the requirements of being easy to learn and inexpensive to integrate into existing workplaces. We conducted a user study with 23 participants which showed that a body leaning metaphor and an accelerometer pedal metaphor performed best. In the given task the participants had to determine the shortest path between various pairs of vertices in a large 3D graph.




Interactive Simulation of Aircraft Noise in Aural and Visual Virtual Environments


Abhishek Sahai, Frank Wefers, Torsten Wolfgang Kuhlen, Eike Stumpf, Michael Vorländer, Sebastian Pick
Applied Acoustics (Journal)(2016)
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This paper describes a novel aircraft noise simulation technique developed at RWTH Aachen University, which makes use of aircraft noise auralization and 3D visualization to make aircraft noise both heard and seen in immersive Virtual Reality (VR) environments. This technique is intended to be used to increase the residents’ acceptance of aircraft noise by presenting noise changes in a more directly relatable form, and also aid in understanding what contributes to the residents’ subjective annoyance via psychoacoustic surveys. This paper describes the technique as well as some of its initial applications. The reasoning behind the development of such a technique is that the issue of aircraft noise experienced by residents in airport vicinities is one of subjective annoyance. Any efforts at noise abatement have been conventionally presented to residents in terms of noise level reductions in conventional metrics such as A-weighted level or equivalent sound level Leq. This conventional approach however proves insufficient in increasing aircraft noise acceptance due to two main reasons – firstly, the residents have only a rudimentary understanding of changes in decibel and secondly, the conventional metrics do not fully capture what the residents actually find annoying i.e. characteristics of aircraft noise they find least acceptable. In order to allow least resistance to air-traffic expansion, the acceptance of aircraft noise has to be increased, for which such a new approach to noise assessment is required.




Vista Widgets: A Framework for Designing 3D User Interfaces from Reusable Interaction Building Blocks


Sascha Gebhardt, Till Petersen-Krauß, B. Sc., Sebastian Pick, Dominik Rausch, Christian Nowke, Thomas Knott, Patric Schmitz, Daniel Zielasko, Bernd Hentschel, Torsten Wolfgang Kuhlen
Proceedings of the 22nd ACM Conference on Virtual Reality Software and Technology (VRST)
pubimg

Virtual Reality (VR) has been an active field of research for several decades, with 3D interaction and 3D User Interfaces (UIs) as important sub-disciplines. However, the development of 3D interaction techniques and in particular combining several of them to construct complex and usable 3D UIs remains challenging, especially in a VR context. In addition, there is currently only limited reusable software for implementing such techniques in comparison to traditional 2D UIs. To overcome this issue, we present ViSTA Widgets, a software framework for creating 3D UIs for immersive virtual environments. It extends the ViSTA VR framework by providing functionality to create multi-device, multi-focus-strategy interaction building blocks and means to easily combine them into complex 3D UIs. This is realized by introducing a device abstraction layer along sophisticated focus management and functionality to create novel 3D interaction techniques and 3D widgets. We present the framework and illustrate its effectiveness with code and application examples accompanied by performance evaluations.

» Show BibTeX

@InProceedings{Gebhardt2016,
Title = {{Vista Widgets: A Framework for Designing 3D User Interfaces from Reusable Interaction Building Blocks}},
Author = {Gebhardt, Sascha and Petersen-Krau, Till and Pick, Sebastian and Rausch, Dominik and Nowke, Christian and Knott, Thomas and Schmitz, Patric and Zielasko, Daniel and Hentschel, Bernd and Kuhlen, Torsten W.},
Booktitle = {Proceedings of the 22nd ACM Conference on Virtual Reality Software and Technology},
Year = {2016},
Address = {New York, NY, USA},
Pages = {251--260},
Publisher = {ACM},
Series = {VRST '16},
Acmid = {2993382},
Doi = {10.1145/2993369.2993382},
ISBN = {978-1-4503-4491-3},
Keywords = {3D interaction, 3D user interfaces, framework, multi-device, virtual reality},
Location = {Munich, Germany},
Numpages = {10},
Url = {http://doi.acm.org/10.1145/2993369.2993382}
}





Experiences on Validation of Multi-Component System Simulations for Medical Training Applications


Yuen Cheong Law Wan, Benjamin Weyers, Torsten Wolfgang Kuhlen
EuroRV3: EuroVis Workshop on Reproducibility, Verification, and Validation in Visualization (2016)
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In the simulation of multi-component systems, we often encounter a problem with a lack of ground-truth data. This situation makes the validation of our simulation methods and models a difficult task. In this work we present a guideline to design validation methodologies that can be applied to the validation of multi-component simulations that lack of ground-truth data. Additionally we present an example applied to an Ultrasound Image Simulation for medical training and give an overview of the considerations made and the results for each of the validation methods. With these guidelines we expect to obtain more comparable and reproducible validation results from which other similar work can benefit.

» Show BibTeX

@InProceedings{eurorv3.20161113,
author = {Law, Yuen C. and Weyers, Benjamin and Kuhlen, Torsten W.},
title = {{Experiences on Validation of Multi-Component System Simulations for Medical Training Applications}},
booktitle = {EuroVis Workshop on Reproducibility, Verification, and Validation in Visualization (EuroRV3)},
year = {2016},
editor = {Kai Lawonn and Mario Hlawitschka and Paul Rosenthal},
publisher = {The Eurographics Association},
doi = {10.2312/eurorv3.20161113},
isbn = {978-3-03868-017-8},
pages = {29--33}
}





Visualizing Performance Data With Respect to the Simulated Geometry


Tom Vierjahn, Torsten Wolfgang Kuhlen, Matthias Stefan Müller, Bernd Hentschel
1st JARA-HPC Symposium, 2016
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Understanding the performance behaviour of high-performance computing (hpc) applications based on performance profiles is a challenging task. Phenomena in the performance behaviour can stem from the hpc system itself, from the application’s code, but also from the simulation domain. In order to analyse the latter phenomena, we propose a system that visualizes profile-based performance data in its spatial context in the simulation domain, i.e., on the geometry processed by the application. It thus helps hpc experts and simulation experts understand the performance data better. Furthermore, it reduces the initially large search space by automatically labeling those parts of the data that reveal variation in performance and thus require detailed analysis.

» Show BibTeX

@inproceedings{VIERJAHN-2016-02,
Author = {Vierjahn, Tom and Kuhlen, Torsten W. and M\"{u}ller, Matthias S. and Hentschel, Bernd},
Booktitle = {JARA-HPC Symposium (accepted for publication)},
Title = {Visualizing Performance Data With Respect to the Simulated Geometry},
Year = {2016}}





Using Directed Variance to Identify Meaningful Views in Call-Path Performance Profiles


Tom Vierjahn, Marc-André Hermanns, Bernd Mohr, Matthias Stefan Müller, Torsten Wolfgang Kuhlen, Bernd Hentschel
3rd Workshop on Visual Performance Analysis (VPA)
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Understanding the performance behaviour of massively parallel high-performance computing (HPC) applications based on call-path performance profiles is a time-consuming task. In this paper, we introduce the concept of directed variance in order to help analysts find performance bottlenecks in massive performance data and in the end optimize the application. According to HPC experts’ requirements, our technique automatically detects severe parts in the data that expose large variation in an application’s performance behaviour across system resources. Previously known variations are effectively filtered out. Analysts are thus guided through a reduced search space towards regions of interest for detailed examination in a 3D visualization. We demonstrate the effectiveness of our approach using performance data of common benchmark codes as well as from actively developed production codes.

» Show BibTeX

@inproceedings{VIERJAHN-2016-04,
Author = {Vierjahn, Tom and Hermanns, Marc-Andr\'{e} and Mohr, Bernd and M\"{u}ller, Matthias S. and Kuhlen, Torsten W. and Hentschel, Bernd},
Booktitle = {3rd Workshop Visual Performance Analysis (to appear)},
Title = {Using Directed Variance to Identify Meaningful Views in Call-Path Performance Profiles},
Year = {2016}}




Poster: Correlating Sub-Phenomena in Performance Data in the Frequency Domain


Tom Vierjahn, Marc-André Hermanns, Bernd Mohr, Matthias Stefan Müller, Torsten Wolfgang Kuhlen, Bernd Hentschel
LDAV 2016 – The 6th IEEE Symposium on Large Data Analysis and Visualization
pubimg

Finding and understanding correlated performance behaviour of the individual functions of massively parallel high-performance computing (HPC) applications is a time-consuming task. In this poster, we propose filtered correlation analysis for automatically locating interdependencies in call-path performance profiles. Transforming the data into the frequency domain splits a performance phenomenon into sub-phenomena to be correlated separately. We provide the mathematical framework and an overview over the visualization, and we demonstrate the effectiveness of our technique.

Best Poster Award!

» Show BibTeX

@inproceedings{Vierjahn-2016-03,
Author = {Vierjahn, Tom and Hermanns, Marc-Andr\'{e} and Mohr, Bernd and M\"{u}ller, Matthias S. and Kuhlen, Torsten W. and Hentschel, Bernd},
Booktitle = {LDAV 2016 -- Posters (accepted)},
Date-Added = {2016-08-31 22:14:47 +0000},
Date-Modified = {2016-08-31 22:15:58 +0000},
Title = {Correlating Sub-Phenomena in Performance Data in the Frequency Domain}
}





Poster: Evaluating Presence Strategies of Temporarily Required Virtual Assistants


Andrea Bönsch, Tom Vierjahn, Torsten Wolfgang Kuhlen
16th International Conference on Intelligent Virtual Agents (IVA), 2016
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Computer-controlled virtual humans can serve as assistants in virtual scenes. Here, they are usually in an almost constant contact with the user. Nonetheless, in some applications assistants are required only temporarily. Consequently, presenting them only when needed, i.e, minimizing their presence time, might be advisable.

To the best of our knowledge, there do not yet exist any design guidelines for such agent-based support systems. Thus, we plan to close this gap by a controlled qualitative and quantitative user study in a CAVE-like environment.We expect users to prefer assistants with a low presence time as well as a low fallback time to get quick support. However, as both factors are linked, a suitable trade-off needs to be found. Thus, we plan to test four different strategies, namely fading, moving, omnipresent and busy. This work presents our hypotheses and our planned within-subject design.

» Show BibTeX

@InBook{Boensch2016c,
Title = {Evaluating Presence Strategies of Temporarily Required Virtual Assistants},
Author = {Andrea B\"{o}nsch and Tom Vierjahn and Torsten W. Kuhlen},
Pages = {387 - 391},
Publisher = {Springer International Publishing},
Year = {2016},
Month = {September},

Abstract = {Computer-controlled virtual humans can serve as assistants in virtual scenes. Here, they are usually in an almost constant contact with the user. Nonetheless, in some applications assistants are required only
temporarily. Consequently, presenting them only when needed, i.e., minimizing their presence time, might be advisable.
To the best of our knowledge, there do not yet exist any design guidelines for such agent-based support systems. Thus, we plan to close this gap by a controlled qualitative and quantitative user study in a CAVE-like environment. We expect users to prefer assistants with a low presence time as well as a low fallback time to get quick support. However, as both factors are linked, a suitable trade-off needs to be found. Thus, we p lan to test four different strategies, namely fading, moving, omnipresent and busy. This work presents our hypotheses and our planned within-subject design.},
Booktitle = {Intelligent Virtual Agents: 16th International Conference, IVA 2016. Proceedings},
Doi = {10.1007/978-3-319-47665-0_39},
Keywords = {Virtual agent, Assistive technology, Immersive virtual environments, User study design},
Owner = {ab280112},
Timestamp = {2016.08.01},
Url = {http://dx.doi.org/10.1007/978-3-319-47665-0_39}
}





An Integrated Approach for the Knowledge Discovery in Computer Simulation Models with a Multi-dimensional Parameter Space


Toufik Al Khawli, Sascha Gebhardt, Urs Eppelt, Torsten Hermanns, Torsten Wolfgang Kuhlen, Wolfgang Schulz
AIP Conference Proceedings, 2016
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In production industries, parameter identification, sensitivity analysis and multi-dimensional visualization are vital steps in the planning process for achieving optimal designs and gaining valuable information. Sensitivity analysis and visualization can help in identifying the most-influential parameters and quantify their contribution to the model output, reduce the model complexity, and enhance the understanding of the model behavior. Typically, this requires a large number of simulations, which can be both very expensive and time consuming when the simulation models are numerically complex and the number of parameter inputs increases. There are three main constituent parts in this work. The first part is to substitute the numerical, physical model by an accurate surrogate model, the so-called metamodel. The second part includes a multi-dimensional visualization approach for the visual exploration of metamodels. In the third part, the metamodel is used to provide the two global sensitivity measures: i) the Elementary Effect for screening the parameters, and ii) the variance decomposition method for calculating the Sobol indices that quantify both the main and interaction effects. The application of the proposed approach is illustrated with an industrial application with the goal of optimizing a drilling process using a Gaussian laser beam.

» Show BibTeX

@article{:/content/aip/proceeding/aipcp/10.1063/1.4952148,
author = "Khawli, Toufik Al and Gebhardt, Sascha and Eppelt, Urs and Hermanns, Torsten and Kuhlen, Torsten and Schulz, Wolfgang",
title = "An integrated approach for the knowledge discovery in computer simulation models with a multi-dimensional parameter space",
journal = "AIP Conference Proceedings",
year = "2016",
volume = "1738",
number = "1",
eid = 370003,
pages = "",
url = "http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4952148;jsessionid=jy3FCznaGWpVQVNPYx765REW.x-aip-live-03",
doi = "http://dx.doi.org/10.1063/1.4952148"
}





Web-based Interactive and Visual Data Analysis for Ubiquitous Learning Analytics


Benjamin Weyers, Christian Nowke, Torsten Wolfgang Kuhlen, Mouri Kousuke, Hiroaki Ogata
Proceedings of the First International Workshop on Learning Analytics Across Physical and Digital Spaces co-located with 6th International Conference on Learning Analytics & Knowledge (LAK 2016)
pubimg

Interactive visual data analysis is a well-established class of methods to gather knowledge from raw and complex data. A broad variety of examples can be found in literature presenting its applicability in various ways and different scientific domains. However, fully fledged solutions for visual analysis addressing learning analytics are still rare. Therefore, this paper will discuss visual and interactive data analysis for learning analytics by presenting best practices followed by a discussion of a general architecture combining interactive visualization employing the Information Seeking Mantra in conjunction with the paradigm of coordinated multiple views. Finally, by presenting a use case for ubiquitous learning analytics its applicability will be demonstrated with the focus on temporal and spatial relation of learning data. The data is gathered from a ubiquitous learning scenario offering information for students to identify learning partners and provides information to teachers enabling the adaption of their learning material.

» Show BibTeX

@InProceedings{weyers2016a,
Title = {Web-based Interactive and Visual Data Analysis for Ubiquitous Learning Analytics},
Author = {Benjamin Weyers, Christian Nowke, Torsten Wolfgang Kuhlen, Mouri Kousuke, Hiroaki Ogata},
Booktitle = {First International Workshop on Learning Analytics Across Physical and Digital Spaces co-located with 6th International Conference on Learning Analytics \& Knowledge (LAK 2016)},
Year = {2016},
Pages = {65--69},
Editor = {Roberto Martinez-Maldonado, Davinia Hernandez-Leo},
Volume = {1601},

Abstract = {Interactive visual data analysis is a well-established class of methods to gather knowledge from raw and complex data. A broad variety of examples can be found in literature presenting its applicability in various ways and different scientific domains. However, fully fledged solutions for visual analysis addressing learning analytics are still rare. Therefore, this paper will discuss visual and interactive data analysis for learning analytics by presenting best practices followed by a discussion of a general architecture combining interactive visualization employing the Information Seeking Mantra in conjunction with the paradigm of coordinated multiple views. Finally, by presenting a use case for ubiquitous learning analytics its applicability will be demonstrated with the focus on temporal and spatial relation of learning data. The data is gathered from a ubiquitous learning scenario offering information
for students to identify learning partners and provides information to teachers enabling the adaption of their learning material.},
Keywords = {interactive analysis, web-based visualization, learning analytics},
Url = {http://ceur-ws.org/Vol-1601/}
}





Poster: Evaluation of Hands-Free HMD-Based Navigation Techniques for Immersive Data Analysis


Daniel Zielasko, Sven Horn, Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference (2016)
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To use the full potential of immersive data analysis when wearing a head-mounted display, the user has to be able to navigate through the spatial data. We collected, developed and evaluated 5 different hands-free navigation methods that are usable while seated in the analyst’s usual workplace. All methods meet the requirements of being easy to learn and inexpensive to integrate into existing workplaces. We conducted a user study with 23 participants which showed that a body leaning metaphor and an accelerometer pedal metaphor performed best within the given task.




Poster: Automatic Generation of World in Miniatures for Realistic Architectural Immersive Virtual Environments


Andrea Bönsch, Sebastian Freitag, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference (2016)
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Orientation and wayfinding in architectural Immersive Virtual Environments (IVEs) are non-trivial, accompanying tasks which generally support the users’ main task. World in Miniatures (WIMs)— essentially 3D maps containing a scene replica—are an established approach to gain survey knowledge about the virtual world, as well as information about the user’s relation to it. However, for largescale, information-rich scenes, scaling and occlusion issues result in diminishing returns. Since there typically is a lack of standardized information regarding scene decompositions, presenting the inside of self-contained scene extracts is challenging.

Therefore, we present an automatic WIM generation workflow for arbitrary, realistic in- and outdoor IVEs in order to support users with meaningfully selected and scaled extracts of the IVE as well as corresponding context information. Additionally, a 3D user interface is provided to manually manipulate the represented extract.

» Show Videos
» Show BibTeX

@InProceedings{Boensch2016b,
Title = {Automatic Generation of World in Miniatures for Realistic Architectural Immersive Virtual Environments},
Author = {Andrea B\"{o}nsch and Sebastian Freitag and Torsten W. Kuhlen},
Booktitle = {IEEE Virtual Reality Conference Poster Proceedings},
Year = {2016},
Pages = {155-156},

Abstract = {Orientation and wayfinding in architectural Immersive Virtual Environments (IVEs) are non-trivial, accompanying tasks which generally support the users’ main task. World in Miniatures (WIMs)—essentially 3D maps containing a scene replica—are an established approach to gain survey knowledge about the virtual world, as well as information about the user’s relation to it. However, for largescale, information-rich scenes, scaling and occlusion issues result in diminishing returns. Since there typically is a lack of standardized information regarding scene decompositions, presenting the inside of self-contained scene extracts is challenging.
Therefore, we present an automatic WIM generation workflow for arbitrary, realistic in- and outdoor IVEs in order to support users with meaningfully selected and scaled extracts of the IVE as well as corresponding context information. Additionally, a 3D user interface is provided to manually manipulate the represented extract.}
}





Poster: Formal Evaluation Strategies for Feature Tracking


Andrea Schnorr, Sebastian Freitag, Dirk Norbert Helmrich, Torsten Wolfgang Kuhlen, Bernd Hentschel
LDAV 2016 – The 6th IEEE Symposium on Large Data Analysis and Visualization
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We present an approach for tracking space-filling features based on a two-step algorithm utilizing two graph optimization techniques. First, one-to-one assignments between successive time steps are found by a matching on a weighted, bi-partite graph. Second, events are detected by computing an independent set on potential event explanations. The main objective of this work is investigating options for formal evaluation of complex feature tracking algorithms in the absence of ground truth data.

» Show BibTeX

@INPROCEEDINGS{Schnorr2016, author = {Andrea Schnorr and Sebastian Freitag and Dirk Helmrich and Torsten W. Kuhlen and Bernd Hentschel}, title = {{F}ormal {E}valuation {S}trategies for {F}eature {T}racking}, booktitle = Proc # { the } # LDAV, year = {2016}, pages = {103--104}, abstract = { We present an approach for tracking space-filling features based on a two-step algorithm utilizing two graph optimization techniques. First, one-to-one assignments between successive time steps are found by a matching on a weighted, bi-partite graph. Second, events are detected by computing an independent set on potential event explanations. The main objective of this work is investigating options for formal evaluation of complex feature tracking algorithms in the absence of ground truth data.
}, doi = { 10.1109/LDAV.2016.7874339}}





Poster: Geometry-Aware Visualization of Performance Data


Tom Vierjahn, Bernd Hentschel, Torsten Wolfgang Kuhlen
EG/VGTC Conference on Visualization, EuroVis 2016
pubimg

Phenomena in the performance behaviour of high-performance computing (HPC) applications can stem from the HPC system itself, from the application's code, but also from the simulation domain. In order to analyse the latter phenomena, we propose a system that visualizes profile-based performance data in its spatial context, i.e., on the geometry, in the simulation domain. It thus helps HPC experts but also simulation experts understand the performance data better. In addition, our tool reduces the initially large search space by automatically labelling large-variation views on the data which require detailed analysis.

» Show BibTeX

@inproceedings {eurp.20161136,
booktitle = {EuroVis 2016 - Posters},
editor = {Tobias Isenberg and Filip Sadlo},
title = {{Geometry-Aware Visualization of Performance Data}},
author = {Vierjahn, Tom and Hentschel, Bernd and Kuhlen, Torsten W.},
year = {2016},
publisher = {The Eurographics Association},
ISBN = {978-3-03868-015-4},
DOI = {10.2312/eurp.20161136},
pages = {37--39}
}





Poster: Tracking Space-Filling Features by Two-Step Optimization


Andrea Schnorr, Sebastian Freitag, Torsten Wolfgang Kuhlen, Bernd Hentschel
EG/VGTC Conference on Visualization, EuroVis 2016
pubimg

We present a novel approach for tracking space-filling features, i.e., a set of features covering the entire domain. The assignment between successive time steps is determined by a two-step, global optimization scheme. First, a maximum-weight, maximal matching on a bi-partite graph is computed to provide one-to-one assignments between features of successive time steps. Second, events are detected in a subsequent step; here the matching step serves to restrict the exponentially large set of potential solutions. To this end, we compute an independent set on a graph representing conflicting event explanations. The method is evaluated by tracking dissipation elements, a structure definition from turbulent flow analysis.

Honorable Mention Award!

» Show BibTeX

@inproceedings {eurp.20161146,
booktitle = {EuroVis 2016 - Posters},
editor = {Tobias Isenberg and Filip Sadlo},
title = {{Tracking Space-Filling Features by Two-Step Optimization}},
author = {Schnorr, Andrea and Freitag, Sebastian and Kuhlen, Torsten W. and Hentschel, Bernd},
year = {2016},
publisher = {The Eurographics Association},
pages = {77--79},
ISBN = {978-3-03868-015-4},
DOI = {10.2312/eurp.20161146}
}





Talk: Two Basic Aspects of Virtual Agents’ Behavior: Collision Avoidance and Presence Strategies


Andrea Bönsch, Tom Vierjahn, Torsten Wolfgang Kuhlen
Virtual Environments: Current Topics in Psychological Research (VECTOR) workshop, 2016

Virtual Agents (VAs) are embedded in virtual environments for two reasons: they enliven architectural scenes by representing more realistic situations, and they are dialogue partners. They can function as training partners such as representing students in a teaching scenario, or as assistants by, e.g., guiding users through a scene or by performing certain tasks either individually or in collaboration with the user. However, designing such VAs is challenging as various requirements have to be met. Two relevant factors will be briefly discussed in the talk: Collision Avoidance and Presence Strategies.




Integrating Visualizations into Modeling NEST Simulations


Christian Nowke, Daniel Zielasko, Benjamin Weyers, Alexander Peyser, Bernd Hentschel, Torsten Wolfgang Kuhlen
Frontiers in Neuroinformatics (Journal)(2015)
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Modeling large-scale spiking neural networks showing realistic biological behavior in their dynamics is a complex and tedious task. Since these networks consist of millions of interconnected neurons, their simulation produces an immense amount of data. In recent years it has become possible to simulate even larger networks. However, solutions to assist researchers in understanding the simulation's complex emergent behavior by means of visualization are still lacking. While developing tools to partially fill this gap, we encountered the challenge to integrate these tools easily into the neuroscientists' daily workflow. To understand what makes this so challenging, we looked into the workflows of our collaborators and analyzed how they use the visualizations to solve their daily problems. We identified two major issues: first, the analysis process can rapidly change focus which requires to switch the visualization tool that assists in the current problem domain. Second, because of the heterogeneous data that results from simulations, researchers want to relate data to investigate these effectively. Since a monolithic application model, processing and visualizing all data modalities and reflecting all combinations of possible workflows in a holistic way, is most likely impossible to develop and to maintain, a software architecture that offers specialized visualization tools that run simultaneously and can be linked together to reflect the current workflow, is a more feasible approach. To this end, we have developed a software architecture that allows neuroscientists to integrate visualization tools more closely into the modeling tasks. In addition, it forms the basis for semantic linking of different visualizations to reflect the current workflow. In this paper, we present this architecture and substantiate the usefulness of our approach by common use cases we encountered in our collaborative work.




Level-of-Detail Modal Analysis for Real-time Sound Synthesis


Dominik Rausch, Bernd Hentschel, Torsten Wolfgang Kuhlen
Workshop on Virtual Reality Interaction and Physical Simulation, 2015
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Modal sound synthesis is a promising approach for real-time physically-based sound synthesis. A modal analysis is used to compute characteristic vibration modes from the geometry and material properties of scene objects. These modes allow an efficient sound synthesis at run-time, but the analysis is computationally expensive and thus typically computed in a pre-processing step. In interactive applications, however, objects may be created or modified at run-time. Unless the new shapes are known upfront, the modal data cannot be pre-computed and thus a modal analysis has to be performed at run-time. In this paper, we present a system to compute modal sound data at run-time for interactive applications. We evaluate the computational requirements of the modal analysis to determine the computation time for objects of different complexity. Based on these limits, we propose using different levels-of-detail for the modal analysis, using different geometric approximations that trade speed for accuracy, and evaluate the errors introduced by lower-resolution results. Additionally, we present an asynchronous architecture to distribute and prioritize modal analysis computations.

» Show BibTeX

@inproceedings {vriphys.20151335,
booktitle = {Workshop on Virtual Reality Interaction and Physical Simulation},
editor = {Fabrice Jaillet and Florence Zara and Gabriel Zachmann},
title = {{Level-of-Detail Modal Analysis for Real-time Sound Synthesis}},
author = {Rausch, Dominik and Hentschel, Bernd and Kuhlen, Torsten W.},
year = {2015},
publisher = {The Eurographics Association},
ISBN = {978-3-905674-98-9},
DOI = {10.2312/vriphys.20151335}
pages = {61--70}
}





Accurate Contact Modeling for Multi-rate Single-point Haptic Rendering of Static and Deformable Environments


Thomas Knott, Torsten Wolfgang Kuhlen
Workshop on Virtual Reality Interaction and Physical Simulation VRIPHYS (2015)
pubimg

Common approaches for the haptic rendering of complex scenarios employ multi-rate simulation schemes. Here, the collision queries or the simulation of a complex deformable object are often performed asynchronously on a lower frequency, while some kind of intermediate contact representation is used to simulate interactions on the haptic rate. However, this can produce artifacts in the haptic rendering when the contact situation quickly changes and the intermediate representation is not able to reflect the changes due to the lower update rate. We address this problem utilizing a novel contact model. It facilitates the creation of contact representations that are accurate for a large range of motions and multiple simulation time-steps.We handle problematic convex contact regions using a local convex decomposition and special constraints for convex areas.We combine our accurate contact model with an implicit temporal integration scheme to create an intermediate mechanical contact representation, which reflects the dynamic behavior of the simulated objects. Moreover, we propose a new iterative solving scheme for the involved constrained dynamics problems.We increase the robustness of our method using techniques from trust region-based optimization. Our approach can be combined with standard methods for the modeling of deformable objects or constraint-based approaches for the modeling of, for instance, friction or joints. We demonstrate its benefits with respect to the simulation accuracy and the quality of the rendered haptic forces in multiple scenarios.

Best Paper Award!




Bimanual Haptic Simulation of Bone Fracturing for the Training of the Bilateral Sagittal Split Osteotomy


Thomas Knott, Torsten Wolfgang Kuhlen
Eurographics Symposium on Virtual Environments (EGVE) (2015)
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In this work we present a haptic training simulator for a maxillofacial procedure comprising the controlled breaking of the lower mandible. To our knowledge the haptic simulation of fracture is seldom addressed, especially when a realistic breaking behavior is required. Our system combines bimanual haptic interaction with a simulation of the bone based on well-founded methods from fracture mechanics. The system resolves the conflict between simulation complexity and haptic real-time constraints by employing a dedicated multi-rate simulation and a special solving strategy for the occurring mechanical equations. Furthermore, we present remeshing-free methods for collision detection and visualization which are tailored for an efficient treatment of the topological changes induced by the fracture. The methods have been successfully implemented and tested in a simulator prototype using real pathological data and a semi-immersive VR-system with two haptic devices. We evaluated the computational efficiency of our methods and show that a stable and responsive haptic simulation of the fracturing has been achieved.




A Framework for Developing Flexible Virtual-Reality-centered Annotation Systems


Sebastian Pick, Torsten Wolfgang Kuhlen
In Proc. of the IEEE Conference on Virtual Reality SEARIS Workshop. (2015)
pubimg

The act of note-taking is an essential part of the data analysis process. It has been realized in form of various annotation systems that have been discussed in many publications. Unfortunately, the focus usually lies on high-level functionality, like interaction metaphors and display strategies. We argue that it is worthwhile to also consider software engineering aspects. Annotation systems often share similar functionality that can potentially be factored into reusable components with the goal to speed up the creation of new annotation systems. At the same time, however, VR-centered annotation systems are not only subject to application-specific requirements, but also to those arising from differences between the various VR platforms, like desktop VR setups or CAVEs. As a result, it is usually necessary to build application-specific VR-centered annotation systems from scratch instead of reusing existing components.

To improve this situation, we present a framework that provides reusable and adaptable building blocks to facilitate the creation of flexible annotation systems for VR applications. We discuss aspects ranging from data representation over persistence to the integration of new data types and interaction metaphors, especially in context of multi-platform applications. To underpin the benefits of such an approach and promote the proposed concepts, we describe how the framework was applied to several of our own projects.




Simulation-based Ultrasound Training Supported by Annotations, Haptics and Linked Multimodal Views


Yuen Cheong Law Wan, Thomas Knott, Sebastian Pick, Benjamin Weyers, Torsten Wolfgang Kuhlen
Eurographics Workshop on Visual Computing for Biology and Medicine (2015)
pubimg

When learning ultrasound (US) imaging, trainees must learn how to recognize structures, interpret textures and shapes, and simultaneously register the 2D ultrasound images to their 3D anatomical mental models. Alleviating the cognitive load imposed by these tasks should free the cognitive resources and thereby improve the learning process. We argue that the amount of cognitive load that is required to mentally rotate the models to match the images to them is too large and therefore negatively impacts the learning process. We present a 3D visualization tool that allows the user to naturally move a 2D slice and navigate around a 3D anatomical model. The slice is displayed in-place to facilitate the registration of the 2D slice in its 3D context. Two duplicates are also shown externally to the model; the first is a simple rendered image showing the outlines of the structures and the second is a simulated ultrasound image. Haptic cues are also provided to the users to help them maneuver around the 3D model in the virtual space. With the additional display of annotations and information of the most important structures, the tool is expected to complement the available didactic material used in the training of ultrasound procedures.




Comparison and Evaluation of Viewpoint Quality Estimation Algorithms for Immersive Virtual Environments


Sebastian Freitag, Benjamin Weyers, Andrea Bönsch, Torsten Wolfgang Kuhlen
Proceedings of the 25th International Conference on Artificial Reality and Telexistence and the 20th Eurographics Symposium on Virtual Environments (ICAT-EGVE), 2015
pubimg

The knowledge of which places in a virtual environment are interesting or informative can be used to improve user interfaces and to create virtual tours. Viewpoint Quality Estimation algorithms approximate this information by calculating quality scores for viewpoints. However, even though several such algorithms exist and have also been used, e.g., in virtual tour generation, they have never been comparatively evaluated on virtual scenes. In this work, we introduce three new Viewpoint Quality Estimation algorithms, and compare them against each other and six existing metrics, by applying them to two different virtual scenes. Furthermore, we conducted a user study to obtain a quantitative evaluation of viewpoint quality. The results reveal strengths and limitations of the metrics on actual scenes, and provide recommendations on which algorithms to use for real applications.

» Show BibTeX

@InProceedings{Freitag2015,
Title = {{Comparison and Evaluation of Viewpoint Quality Estimation Algorithms for Immersive Virtual Environments}},
Author = {Freitag, Sebastian and Weyers, Benjamin and B\"{o}nsch, Andrea and Kuhlen, Torsten W.},
Booktitle = {ICAT-EGVE 2015 - International Conference on Artificial Reality and Telexistence and Eurographics Symposium on Virtual Environments},
Year = {2015},
Pages = {53-60},
Doi = {10.2312/egve.20151310}
}





Low-Cost Vision-Based Multi-Person Foot Tracking for CAVE Systems with Under-Floor Projection


Sebastian Freitag, Sebastian Schmitz, Benjamin Weyers, Torsten Wolfgang Kuhlen
Virtuelle und Erweiterte Realität: 12. Workshop der GI-Fachgruppe VR/AR (2015)
pubimg

In this work, we present an approach for tracking the feet of multiple users in CAVE-like systems with under-floor projection. It is based on low-cost consumer cameras, does not require users to wear additional equipment, and can be installed without modifying existing components. If the brightness of the floor projection does not contain too much variation, the feet of several people can be successfully and precisely tracked and assigned to individuals. The tracking data can be used to enable or enhance user interfaces like Walking-in-Place or torso-directed steering, provide audio feedback for footsteps, and improve the immersive experience for multiple users.




BlowClick: A Non-Verbal Vocal Input Metaphor for Clicking


Daniel Zielasko, Sebastian Freitag, Dominik Rausch, Yuen Cheong Law Wan, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proc. of 3rd Symposium on Spatial User Interaction (2015)
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In contrast to the wide-spread use of 6-DOF pointing devices, freehand user interfaces in Immersive Virtual Environments (IVE) are non-intrusive. However, for gesture interfaces, the definition of trigger signals is challenging. The use of mechanical devices, dedicated trigger gestures, or speech recognition are often used options, but each comes with its own drawbacks. In this paper, we present an alternative approach, which allows to precisely trigger events with a low latency using microphone input. In contrast to speech recognition, the user only blows into the microphone. The audio signature of such blow events can be recognized quickly and precisely. The results of a user study show that the proposed method allows to successfully complete a standard selection task and performs better than expected against a standard interaction device, the Flystick.




Cirque des Bouteilles: The Art of Blowing on Bottles


Daniel Zielasko, Dominik Rausch, Yuen Cheong Law Wan, Thomas Knott, Sebastian Pick, Sven Porsche, Joachim Herber, Johannes Hummel, Torsten Wolfgang Kuhlen
Proc. of IEEE 10th Symposium on 3D User Interfaces (2015)
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Making music by blowing on bottles is fun but challenging. We introduce a novel 3D user interface to play songs on virtual bottles. For this purpose the user blows into a microphone and the stream of air is recreated in the virtual environment and redirected to virtual bottles she is pointing to with her fingers. This is easy to learn and subsequently opens up opportunities for quickly switching between bottles and playing groups of them together to form complex melodies. Furthermore, our interface enables the customization of the virtual environment, by means of moving bottles, changing their type or filling level.

» Show Videos



Packet-Oriented Streamline Tracing on Modern SIMD Architectures


Bernd Hentschel, Jens Henrik Göbbert, Michael Klemm, Paul Springer, Andrea Schnorr, Torsten Wolfgang Kuhlen
Eurographics Symposium on Parallel Graphics and Visualization (2015)
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The advection of integral lines is an important computational kernel in vector field visualization. We investigate how this kernel can profit from vector (SIMD) extensions in modern CPUs. As a baseline, we formulate a streamline tracing algorithm that facilitates auto-vectorization by an optimizing compiler. We analyze this algorithm and propose two different optimizations. Our results show that particle tracing does not per se benefit from SIMD computation. Based on a careful analysis of the auto-vectorized code, we propose an optimized data access routine and a re-packing scheme which increases average SIMD efficiency. We evaluate our approach on three different, turbulent flow fields. Our optimized approaches increase integration performance up to 5:6 over our baseline measurement. We conclude with a discussion of current limitations and aspects for future work.

» Show BibTeX

@INPROCEEDINGS{Hentschel2015,
author = {Bernd Hentschel and Jens Henrik G{\"o}bbert and Michael Klemm and
Paul Springer and Andrea Schnorr and Torsten W. Kuhlen},
title = {{P}acket-{O}riented {S}treamline {T}racing on {M}odern {SIMD}
{A}rchitectures},
booktitle = {Proceedings of the Eurographics Symposium on Parallel Graphics
and Visualization},
year = {2015},
pages = {43--52},
abstract = {The advection of integral lines is an important computational
kernel in vector field visualization. We investigate
how this kernel can profit from vector (SIMD) extensions in modern CPUs. As a
baseline, we formulate a streamline
tracing algorithm that facilitates auto-vectorization by an optimizing compiler.
We analyze this algorithm and
propose two different optimizations. Our results show that particle tracing does
not per se benefit from SIMD computation.
Based on a careful analysis of the auto-vectorized code, we propose an optimized
data access routine
and a re-packing scheme which increases average SIMD efficiency. We evaluate our
approach on three different,
turbulent flow fields. Our optimized approaches increase integration performance
up to 5.6x over our baseline
measurement. We conclude with a discussion of current limitations and aspects
for future work.}
}





An Integrative Tool Chain for Collaborative Virtual Museums in Immersive Virtual Environments


Daniel Sacher, Benjamin Weyers, Torsten Wolfgang Kuhlen, Wolfram Luther
Proceedings of 21st International Conference on Collaboration and Technology (CRIWG) (2015)

Various conceptual approaches for the creation and presentation of virtual museums can be found. However, less work exists that concentrates on collaboration in virtual museums. The support of collaboration in virtual museums provides various benefits for the visit as well as the preparation and creation of virtual exhibits. This paper addresses one major problem of collaboration in virtual museums: the awareness of visitors. We use a Cave Automated Virtual Environment (CAVE) for the visualization of generated virtual museums to offer simple awareness through co-location. Furthermore, the use of smartphones during the visit enables the visitors to create comments or to access exhibit related metadata. Thus, the main contribution of this ongoing work is the presentation of a workflow that enables an integrated deployment of generic virtual museums into a CAVE, which will be demonstrated by deploying the virtual Leopold Fleischhacker Museum.




Poster: Scalable Metadata In- and Output for Multi-platform Data Annotation Applications


Sebastian Pick, Sascha Gebhardt, Bernd Hentschel, Torsten Wolfgang Kuhlen
Proceedings of IEEE Virtual Reality Conference (2015)
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Metadata in- and output are important steps within the data annotation process. However, selecting techniques that effectively facilitate these steps is non-trivial, especially for applications that have to run on multiple virtual reality platforms. Not all techniques are applicable to or available on every system, requiring to adapt workflows on a per-system basis. Here, we describe a metadata handling system based on Android's Intent system that automatically adapts workflows and thereby makes manual adaption needless.




Poster: Vision-based Multi-Person Foot Tracking for CAVE Systems with Under-Floor Projection


Sebastian Freitag, Sebastian Schmitz, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Virtual Reality Conference (2015)
pubimg

In this work, we present an approach for tracking the feet of mul- tiple users in CAVE-like systems with under-floor projection. It is based on low-cost consumer cameras, does not require users to wear additional equipment, and can be installed without modifying existing components. If the brightness of the floor projection does not contain too much variation, the feet of several people can be reliably tracked and assigned to individuals.




Poster: Effects and Applicability of Rotation Gain in CAVE-like Environments


Sebastian Freitag, Benjamin Weyers, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Virtual Reality Conference (2015)
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In this work, we report on a pilot study we conducted, and on a study design, to examine the effects and applicability of rotation gain in CAVE-like virtual environments. The results of the study will give recommendations for the maximum levels of rotation gain that are reasonable in algorithms for enlarging the virtual field of regard or redirected walking.




Poster: flapAssist: How the Integration of VR and Visualization Tools Fosters the Factory Planning Process


Sascha Gebhardt, Sebastian Pick, Hanno Voet, Julian Utsch, Toufik Al Khawli, Urs Eppelt, Rudolf Reinhard, Christian Büscher, Bernd Hentschel, Torsten Wolfgang Kuhlen
Proceedings of the IEEE Virtual Reality Conference (2015)
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Virtual Reality (VR) systems are of growing importance to aid decision support in the context of the digital factory, especially factory layout planning. While current solutions either focus on virtual walkthroughs or the visualization of more abstract information, a solution that provides both, does currently not exist. To close this gap, we present a holistic VR application, called Factory Layout Planning Assistant (flapAssist). It is meant to serve as a platform for planning the layout of factories, while also providing a wide range of analysis features. By being scalable from desktops to CAVEs and providing a link to a central integration platform, flapAssist integrates well in established factory planning workflows.




Poster: Tracking Space-Filling Structures in Turbulent Flows


Andrea Schnorr, Jens Henrik Göbbert, Torsten Wolfgang Kuhlen, Bernd Hentschel
Large Data Analysis and Visualization (LDAV), 2015
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We present a novel approach for tracking space-filling features, i.e. a set of features which covers the entire domain. In contrast to previous work, we determine the assignment between features from successive time steps by computing a globally optimal, maximum-weight, maximal matching on a weighted, bi-partite graph. We demonstrate the method's functionality by tracking dissipation elements (DEs), a space-filling structure definition from turbulent flow analysis. The ability to track DEs over time enables researchers from fluid mechanics to extend their analysis beyond the assessment of static flow fields to time-dependent settings.

» Show BibTeX

@INPROCEEDINGS{Schnorr2015,
author = {Andrea Schnorr and Jens-Henrik Goebbert and Torsten W. Kuhlen and Bernd Hentschel},
title = {{T}racking {S}pace-{F}illing {S}tructures in {T}urbulent {F}lows},
booktitle = Proc # { the } # LDAV,
year = {2015},
pages = {143--144},
abstract = {We present a novel approach for tracking space-filling features, i.e. a set of features which covers the entire domain. In contrast to previous work, we determine the assignment between features from successive time steps by computing a globally optimal, maximum-weight, maximal matching on a weighted, bi-partite graph. We demonstrate the method's functionality by tracking dissipation elements (DEs), a space-filling structure definition from turbulent flow analysis. The abilitytotrack DEs over time enables researchers from fluid mechanics to extend their analysis beyond the assessment of static flow fields to time-dependent settings.},
doi = {10.1109/LDAV.2015.7348089},
keywords = {Feature Tracking, Weighted, Bi-Partite Matching, Flow
Visualization, Dissipation Elements}
}





Ein Konzept zur Integration von Virtual Reality Anwendungen zur Verbesserung des Informationsaustauschs im Fabrikplanungsprozess - A Concept for the Integration of Virtual Reality Applications to Improve the Information Exchange within the Factory Planning Process


Sebastian Pick, Sascha Gebhardt, Bernd Hentschel, Torsten Wolfgang Kuhlen, Rudolf Reinhard, Christian Büscher, Toufik Al Khawli, Urs Eppelt, Hanno Voet, Julian Utsch
(National Publication In) Tagungsband 12. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung (German, 2015)
pubimg

Factory planning is a highly heterogeneous process that involves various expert groups at the same time. In this context, the communication between different expert groups poses a major challenge. One reason for this lies in the differing domain knowledge of individual groups. However, since decisions made within one domain usually have an effect on others, it is essential to make these domain interactions visible to all involved experts in order to improve the overall planning process. In this paper, we present a concept that facilitates the integration of two separate virtual-reality- and visualization analysis tools for different application domains of the planning process. The concept was developed in context of the Virtual Production Intelligence and aims at creating an approach to making domain interactions visible, such that the aforementioned challenges can be mitigated.

» Show BibTeX

@Article{Pick2015,
Title = {“Ein Konzept zur Integration von Virtual Reality Anwendungen zur Verbesserung des Informationsaustauschs im Fabrikplanungsprozess”},
Author = {S. Pick, S. Gebhardt, B. Hentschel, T. W. Kuhlen, R. Reinhard, C. Büscher, T. Al Khawli, U. Eppelt, H. Voet, and J. Utsch},
Journal = {Tagungsband 12. Paderborner Workshop Augmented \& Virtual Reality in der Produktentstehung},
Year = {2015},
Pages = {139--152}
}




Ein Ansatz zur Softwaretechnischen Integration von Virtual Reality Anwendungen am Beispiel des Fabrikplanungsprozesses - An Approach for the Softwaretechnical Integration of Virtual Reality Applications by the Example of the Factory Planning Process


Sascha Gebhardt, Sebastian Pick, Bernd Hentschel, Torsten Wolfgang Kuhlen, Christian Büscher, Rudolf Reinhard
(National Publication In) Tagungsband 12. Paderborner Workshop Augmented & Virtual Reality in der Produktentstehung (German, 2015)
pubimg

The integration of independent applications is a complex task from a software engineering perspective. Nonetheless, it entails significant benefits, especially in the context of Virtual Reality (VR) supported factory planning, e.g., to communicate interdependencies between different domains. To emphasize this aspect, we integrated two independent VR and visualization applications into a holistic planning solution. Special focus was put on parallelization and interaction aspects, while also considering more general requirements of such an integration process. In summary, we present technical solutions for the effective integration of several VR applications into a holistic solution with the integration of two applications from the context of factory planning with special focus on parallelism and interaction aspects. The effectiveness of the approach is demonstrated by performance measurements.

» Show BibTeX

@Article{Gebhardt2015,
Title = {“Ein Ansatz zur Softwaretechnischen Integration von Virtual Reality Anwendungen am Beispiel des Fabrikplanungsprozesses”},
Author = {S. Gebhardt, S. Pick, B. Hentschel, T. W. Kuhlen, R. Reinhard, and C. Büscher},
Journal = {Tagungsband 12. Paderborner Workshop Augmented \& Virtual Reality in der Produktentstehung},
Year = {2015},
Pages = {153--166}
}




Immersive Art: Using a CAVE-like Virtual Environment for the Presentation of Digital Works of Art


Sebastian Pick, Andrea Bönsch, Dennis Scully, Torsten Wolfgang Kuhlen
Virtuelle und Erweiterte Realität, 12. Workshop der GI-Fachgruppe VR/AR (2015)
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Digital works of art are often created using some kind of modeling software, like Cinema4D. Usually they are presented in a non-interactive form, like large Diasecs, and can thus only be experienced by passive viewing. To explore alternative, more captivating presentation channels, we investigate the use of a CAVE virtual reality (VR) system as an immersive and interactive presentation platform in this paper. To this end, in a collaboration with an artist, we built an interactive VR experience from one of his existing works. We provide details on our design and report on the results of a qualitative user study.

» Show Videos
» Show BibTeX

@Article{Pick2015,
Title = {{Immersive Art: Using a CAVE-like Virtual Environment for the Presentation of Digitial Works of Art}},
Author = {Pick, Sebastian and B\"{o}nsch, Andrea and Scully, Dennis and Kuhlen, Torsten W.},
Journal = {{V}irtuelle und {E}rweiterte {R}ealit\"at, 12. {W}orkshop der {GI}-{F}achgruppe {VR}/{AR}},
Year = {2015},
Pages = {10-21},
ISSN = {978-3-8440-3868-2},
Publisher = {Shaker Verlag}
}





Efficient Modal Sound Synthesis on GPUs


Dominik Rausch, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE VR Workshop: Sonic Interaction in Virtual Environments (2014)
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Modal sound synthesis is a useful method to interactively generate sounds for Virtual Environments. Forces acting on objects excite modes, which then have to be accumulated to generate the output sound. Due to the high audio sampling rate, algorithms using the CPU typically can handle only a few actively sounding objects. Additionally, force excitation should be applied at a high sampling rate. We present different algorithms to compute the synthesized sound using a GPU, and compare them to CPU implementations. The GPU algorithms shows a significantly higher performance, and allows many sounding objects simultaneously.




Quo Vadis CAVE – Does Immersive Visualization Still Matter?


Torsten Wolfgang Kuhlen, Bernd Hentschel
IEEE Computer Graphics and Applications Journal
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More than two decades have passed since the introduction of the CAVE (Cave Automatic Virtual Environment), a landmark in the development of VR.1 The CAVE addressed two major issues with head-mounted displays of the era. First, it provided an unprecedented field of view, greatly improving the Feeling of presence in a virtual environment (VE). Second, this feeling was ampli ed because users didn’t have to rely on a virtual representation of their own bodies or parts thereof. Instead, they could physically enter the virtual space. Scientific visualization had been promulgated as a killer app for VR technology almost from day one. With the CAVE’s inception, it became possible to “put users within their data.” Proponents predicted two key advantages. First, immersive VR promised faster, more comprehensive understanding of complex, spatial relationships owing to head-tracked, stereoscopic rendering. Second, it would provide a more natural user interface, specifically for spatial interaction. In a seminal article, Andy van Dam and his colleagues proposed VR-enabled visualization as a midterm solution to the “accelerating data crisis.”2 That is, the ability to generate data had for some time outpaced the ability to analyze it. Over the years, a number of studies have investigated the effects of VR-based visualizations in speci c application scenarios. Recently, Bireswar Laha and his colleagues provided more general, empirical evidence for its benefits. Although VR and scienti c visualization have matured and many of the original technical limitations have been resolved, immersive visualization has yet to  nd the widespread, everyday use that was claimed in the early days. At the same time, the demand for scalable visualization solutions is greater than ever. If anything, the gap between data generation and analysis capabilities has widened even more. So, two questions arise. What should such scalable solutions look like, and what requirements arise regarding the underlying hardware and software and the overall methodology?




Preliminary Bone Sawing Model for a Virtual Reality-Based Training Simulator of Bilateral Sagittal Split Osteotomy


Thomas Knott, Raluca Sofronia, Marcus Gerressen, Yuen Cheong Law Wan, Arjana Davidescu, Gerorg Savii, Karls H. Gatzweiler, Manfred Staat, Torsten Wolfgang Kuhlen
International Symposium on Biomedical Simulation (2014)
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Successful bone sawing requires a high level of skill and experience, which could be gained by the use of Virtual Reality-based simulators. A key aspect of these medical simulators is realistic force feedback. The aim of this paper is to model the bone sawing process in order to develop a valid training simulator for the bilateral sagittal split osteotomy, the most often applied corrective surgery in case of a malposition of the mandible. Bone samples from a human cadaveric mandible were tested using a designed experimental system. Image processing and statistical analysis were used for the selection of four models for the bone sawing process. The results revealed a polynomial dependency between the material removal rate and the applied force. Differences between the three segments of the osteotomy line and between the cortical and cancellous bone were highlighted.




Virtuelle Realität als Gegenstand und Werkzeug der Wissenschaft


Torsten Wolfgang Kuhlen
Exploring Virtuality, Springer (2014)

Dieser Beitrag stellt die Disziplin der Virtuellen Realität (VR) als eine wichtige Ausprägung von Virtualität vor. Die VR wird als eine spezielle Form der Mensch-Computer-Schnittstelle verstanden, die mehrere menschliche Sinne in die Interaktion einbezieht und beim Benutzer die Illusion hervorruft, eine computergenerierte künstliche Welt als real wahrzunehmen. Der Beitrag zeigt auf, dass umfangreiche Methodenforschung über mehrere Disziplinen hinweg notwendig ist um dieses ultimative Ziel zu erreichen oder ihm zumindest näher zu kommen. Schließlich werden drei unterschiedliche Anwendungen vorgestellt welche demonstrieren, auf welch vielfältige Art und Weise die VR als Werkzeug in den Wissenschaften eingesetzt werden kann.



Reorientation in Virtual Environments using Interactive Portals


Sebastian Freitag, Dominik Rausch, Torsten Wolfgang Kuhlen
IEEE Symposium on 3D User Interfaces (3DUI) (2014)
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Real walking is the most natural method of navigation in virtual environments. However, physical space limitations often prevent or complicate its continuous use. Thus, many real walking interfaces, among them redirected walking techniques, depend on a reorientation technique that redirects the user away from physical boundaries when they are reached. However, existing reorientation techniques typically actively interrupt the user, or depend on the application of rotation gain that can lead to simulator sickness. In our approach, the user is reoriented using portals. While one portal is placed automatically to guide the user to a safe position, she controls the target selection and physically walks through the portal herself to perform the reorientation. In a formal user study we show that the method does not cause additional simulator sickness, and participants walk more than with point-and-fly navigation or teleportation, at the expense of longer completion times.

Best Technote!

» Show BibTeX

@INPROCEEDINGS{freitag2014,
author={S. Freitag and D. Rausch and T. Kuhlen},
booktitle={2014 IEEE Symposium on 3D User Interfaces (3DUI)},
title={{Reorientation in Virtual Environments Using Interactive Portals}},
year={2014},
pages={119-122},
doi={10.1109/3DUI.2014.6798852},
month={March},
}





Advanced Virtual Reality and Visualization Support for Factory Layout Planning


Sebastian Pick, Sascha Gebhardt, Kai Kreisköther, Rudolf Reinhard, Hanno Voet, Christian Büscher, Torsten Wolfgang Kuhlen
Entwerfen Entwickeln Erleben: Beiträge zur virtuellen Produktentwicklung und Konstruktionstechnik, Dresden (2014)
pubimg

Recently, more and more Virtual Reality (VR) and visualization solutions to support the factory layout planning process have been presented. On the one hand, VR enables planners to create cost-effective virtual prototypes and to perform virtual walkthroughs, e.g., to verify proposed layouts. On the other hand, visualization helps to gain insight into simulation results that, e.g., describe the various interdependencies between machines, such as material flows. In order to create truly effective tools based on VR and visualization, the right techniques have to be chosen and adapted to the specific problem. However, the solutions published so far usually do not exploit these technologies to their full potential.
To address this situation, we present a VR-based planning assistant that offers advanced visualization functionality that furthers the understanding of planning-relevant parameters, while also relying on established techniques. In order to realize a useful approach, the assistant fulfills three central requirements:

  1. A smooth integration of the assistant into existing workflows is essential in order to not disrupt them. Consequently, existing tools need to be properly integrated and a mechanism for data exchange with these tools has to be provided.
  2. Visualization is the main means of facilitating insight. Instead of only displaying factory models, advanced techniques to visualize more abstract quantities, like material flows or process chains, have to be provided.
  3. VR systems vary in the degree of immersion they offer, ranging from non-immersive desktop systems to fully immersive Cave Automatic Virtual Environment (CAVE) systems. Scalability among these systems allows adapting high-end installations as well as cost-effective solutions. However, to ensure good scalability, devising a flexible system abstraction and a unified interaction concept are essential.
The purpose of this paper is twofold. First, our VR-based planning assistant is introduced and realization details are presented. Second, by presenting technical details of the used techniques we aim at providing VR and visualization guidelines for the creation or extension of VR-based factory layout planning tools.
The base for our planning assistant is an immersive VR (IVR) system in form of a CAVE. Our solution allows performing virtual walkthroughs and offers additional visualization techniques for planning relevant data.



A 3D Collaborative Virtual Environment to Integrate Immersive Virtual Reality into Factory Planning Processes


Sebastian Pick, Sascha Gebhardt, Benjamin Weyers, Bernd Hentschel, Torsten Wolfgang Kuhlen
International Workshop on Collaborative Virtual Environments (3DCVE)(2014)

In the recent past, efforts have been made to adopt immersive virtual reality (IVR) systems as a means for design reviews in factory layout planning. While several solutions for this scenario have been developed, their integration into existing planning workflows has not been discussed yet. From our own experience of developing such a solution, we conclude that the use of IVR systems-like CAVEs-is rather disruptive to existing workflows. One major reason for this is that IVR systems are not available everywhere due to their high costs and large physical footprint. As a consequence, planners have to travel to sites offering such systems which is especially prohibitive as planners are usually geographically dispersed. In this paper, we present a concept for integrating IVR systems into the factory planning process by means of a 3D collaborative virtual environment (3DCVE) without disrupting the underlying planning workflow. The goal is to combine non-immersive and IVR systems to facilitate collaborative walkthrough sessions. However, this scenario poses unique challenges to interactive collaborative work that to the best of our knowledge have not been addressed so far. In this regard, we discuss approaches to viewpoint sharing, telepointing and annotation support that are geared towards distributed heterogeneous 3DCVEs.




Geometrically Limited Constraints for Physics-based Haptic Rendering


Thomas Knott, Torsten Wolfgang Kuhlen
Eurohaptics 2014
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In this paper a single-point haptic rendering technique is proposed which uses a constraint-based physics simulation approach. Geometries are sampled using point shell points, each associated with a small disk, that jointly result in a closed surface for the whole shell. The geometric information is incorporated into the constraint-based simulation using newly introduced geometrically limited contact constraints which are active in a restricted region corresponding to the disks in contact. The usage of disk constraints not only creates closed surfaces, which is important for single-point rendering, but also tackles the problem of over-constraint contact situations in convex geometric setups. Furthermore, an iterative solving scheme for dynamic problems under consideration of the proposed constraint type is proposed. Finally, an evaluation of the simulation approach shows the advantages compared to standard contact constraints regarding the quality of the rendered forces.




Data-flow Oriented Software Framework for the Development of Haptic-enabled Physics Simulations


Thomas Knott, Benjamin Weyers, Bernd Hentschel, Torsten Wolfgang Kuhlen
Software Engineering and Architectures for Realtime Interactive Systems (2014)
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This paper presents a software framework that supports the development of haptic-enabled physics simulations. The framework provides tools aiming to facilitate a fast prototyping process by utilizing component and flow-oriented architectures, while maintaining the capability to create efficient code which fulfills the performance requirements induced by the target applications. We argue that such a framework should not only ease the creation of prototypes but also help to effectively and efficiently evaluate them. To this end, we provide analysis tools and the possibility to build problem oriented evaluation environments based on the described software concepts. As motivating use case, we present a project with the goal to develop a haptic-enabled medical training simulator for a maxillofacial procedure. With this example, we demonstrate how the described framework can be used to create a simulation architecture for a complex haptic simulation and how the tools assist in the prototyping process.




An Evaluation of a Smart-Phone-Based Menu System for Immersive Virtual Environments


Sascha Gebhardt, Sebastian Pick, Thomas Oster, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE Symposium on 3D User Interfaces (3DUI)(2014)
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System control is a crucial task for many virtual reality applications and can be realized in a broad variety of ways, whereat the most common way is the use of graphical menus. These are often implemented as part of the virtual environment, but can also be displayed on mobile devices. Until now, many systems and studies have been published on using mobile devices such as personal digital assistants (PDAs) to realize such menu systems. However, most of these systems have been proposed way before smartphones existed and evolved to everyday companions for many people. Thus, it is worthwhile to evaluate the applicability of modern smartphones as carrier of menu systems for immersive virtual environments. To do so, we implemented a platform-independent menu system for smartphones and evaluated it in two different ways. First, we performed an expert review in order to identify potential design flaws and to test the applicability of the approach for demonstrations of VR applications from a demonstrator's point of view. Second, we conducted a user study with 21 participants to test user acceptance of the menu system. The results of the two studies were contradictory: while experts appreciated the system very much, user acceptance was lower than expected. From these results we could draw conclusions on how smartphones should be used to realize system control in virtual environments and we could identify connecting factors for future research on the topic.




Integration of VR and Visualization Tools to Foster the Factory Planning Process


Sascha Gebhardt, Sebastian Pick, Toufik Al Khawli, Hanno Voet, Rudolf Reinhard, Bernd Hentschel, Torsten Wolfgang Kuhlen
IFF-Wissenschaftstage (2014)
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Recently, virtual reality (VR) and visualization have been increasingly employed to facilitate various tasks in factory planning processes. One major challenge in this context lies in the exchange of information between expert groups concerned with distinct planning tasks in order to make planners aware of inter-dependencies. For example, changes to the configuration of individual machines can have an effect on the overall production performance and vice versa. To this end, we developed VR- and visualization-based planning tools for two distinct planning tasks for which we present an integration concept that facilitates information exchange between these tools. The first application's goal is to facilitate layout planning by means of a CAVE system. The high degree of immersion offered by this system allows users to judge spatial relations in entire factories through cost-effective virtual walkthroughs. Additionally, information like material flow data can be visualized within the virtual environment to further assist planners to comprehensively evaluate the factory layout. Another application focuses on individual machines with the goal to help planners find ideal configurations by providing a visualization solution to explore the multi-dimensional parameter space of a single machine. This is made possible through the use of meta-models of the parameter space that are then visualized by means of the concept of Hyperslice. In this paper we present a concept that shows how these applications can be integrated into one comprehensive planning tool that allows for planning factories while considering factors of different planning levels at the same time. The concept is backed by Virtual Production Intelligence (VPI), which integrates data from different levels of factory processes, while including additional data sources and algorithms to provide further information to be used by the applications. In conclusion, we present an integration concept for VR- and visualization-based software tools that facilitates the communication of interdependencies between different factory planning tasks. As the first steps towards creating a comprehensive factory planning solution, we demonstrate the integration of the aforementioned two use-cases by applying VPI. Finally, we review the proposed concept by discussing its benefits and pointing out potential implementation pitfalls.



An Unusual Linker and an Unexpected Node: CaCl2 Dumbbells Linked by Proline to Form Square Lattice Networks


Kevin Lamberts, Sven Porsche, Bernd Hentschel, Torsten Wolfgang Kuhlen, Ulli Englert
CrystEngComm (2014)
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Four new structures based on CaCl2 and proline are reported, all with an unusual Cl–Ca–Cl moiety. Depending on the stoichiometry and the chirality of the amino acid, this metal dihalide fragment represents the core of a mononuclear Ca complex or may be linked by the carboxylate to form extended structures. A cisoid coordination of the halide atoms at the calcium cation is encountered in a chain polymer. In the 2D structures, CaCl2 dumbbells act as nodes and are crosslinked by either enantiomerically pure or racemic proline to form square lattice nets. Extensive database searches and topology tests prove that this structure type is rare for MCl2 dumbbells in general and unprecedented for Ca compounds.Four new structures based on CaCl2 and proline are reported, all with an unusual Cl–Ca–Cl moiety. Depending on the stoichiometry and the chirality of the amino acid, this metal dihalide fragment represents the core of a mononuclear Ca complex or may be linked by the carboxylate to form extended structures. A cisoid coordination of the halide atoms at the calcium cation is encountered in a chain polymer. In the 2D structures, CaCl2 dumbbells act as nodes and are crosslinked by either enantiomerically pure or racemic proline to form square lattice nets. Extensive database searches and topology tests prove that this structure type is rare for MCl2 dumbbells in general and unprecedented for Ca compounds.

» Show BibTeX

@Article{Lamberts2014,
Title = {{An Unusual Linker and an Unexpected Node: CaCl2 Dumbbells Linked by Proline to Form Square Lattice Networks}},
Author = {Lamberts, Kevin and Porsche, Sven and Hentschel, Bernd and Kuhlen, Torsten and Englert, Ulli},
Journal = {CrystEngComm},
Year = {2014},
Pages = {3305-3311},
Volume = {16},
Doi = {10.1039/C3CE42357C},
Issue = {16},
Publisher = {The Royal Society of Chemistry},
Url = {http://dx.doi.org/10.1039/C3CE42357C}
}





The Human Brain Project - Chances and Challenges for Cognitive Systems


Benjamin Weyers, Christian Nowke, Claudia Hänel, Daniel Zielasko, Bernd Hentschel, Torsten Wolfgang Kuhlen
Proceedings 3. of the Interdisziplinärer Workshop Kognitive Systeme: Mensch, Teams, Systeme und Automaten (2014)

The Human Brain Project is one of the largest scientific initiatives dedicated to the research of the human brain worldwide. Over 80 research groups from a broad variety of scientific areas, such as neuroscience, simulation science, high performance computing, robotics, and visualization work together in this European research initiative. This work at hand will identify certain chances and challenges for cognitive systems engineering resulting from the HBP research activities. Beside the main goal of the HBP gathering deeper insights into the structure and function of the human brain, cognitive system research can directly benefit from the creation of cognitive architectures, the simulation of neural networks, and the application of these in context of (neuro-)robotics. Nevertheless, challenges arise regarding the utilization and transformation of these research results for cognitive systems, which will be discussed in this paper. Tools necessary to cope with these challenges are visualization techniques helping to understand and gain insights into complex data. Therefore, this paper presents a set of visualization techniques developed at the Virtual Reality Group at the RWTH Aachen University.

» Show BibTeX

@inproceedings{Weyers2014,
author = {Weyers, Benjamin and Nowke, Christian and H{\"{a}}nel, Claudia and Zielasko, Daniel and Hentschel, Bernd and Kuhlen, Torsten},
booktitle = {Workshop Kognitive Systeme: Mensch, Teams, Systeme und Automaten},
title = {{The Human Brain Project – Chances and Challenges for Cognitive Systems}},
year = {2014}
}





Interactive Volume Rendering for Immersive Virtual Environments


Claudia Hänel, Benjamin Weyers, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE VIS International Workshop on 3DVis: Does 3D really make sense for Data Visualization (2014)

Immersive virtual environments (IVEs) are an appropriate platform for 3D data visualization and exploration as, for example, the spatial understanding of these data is facilitated by stereo technology. However, in comparison to desktop setups a lower latency and thus a higher frame rate is mandatory. In this paper we argue that current realizations of direct volume rendering do not allow for a desirable visualization w.r.t. latency and visual quality that do not impair the immersion in virtual environments. To this end, we analyze published acceleration techniques and discuss their potential in IVEs; furthermore, head tracking is considered as a main challenge but also a starting point for specific optimization techniques.

» Show BibTeX

@inproceedings{Hanel2014,
author = {H{\"{a}}nel, Claudia and Weyers, Benjamin and Hentschel, Bernd and Kuhlen, Torsten W.},
booktitle = {IEEE VIS International Workshop on 3DVis: Does 3D really make sense for Data Visualization?},
title = {{Interactive Volume Rendering for Immersive Virtual Environments}},
year = {2014}
}





Visualization of Memory Access Behavior on Hierarchical NUMA Architectures


Benjamin Weyers, Christian Terboven, Dirk Schmidl, Joachim Herber, Torsten Wolfgang Kuhlen, Matthias Stefan Müller, Bernd Hentschel
Proceedings of the First Workshop on Visual Performance Analysis (2014)

The available memory bandwidth of existing high performance computing platforms turns out as being more and more the limitation to various applications. Therefore, modern microarchitectures integrate the memory controller on the processor chip, which leads to a non-uniform memory access behavior of such systems. This access behavior in turn entails major challenges in the development of shared memory parallel applications. An improperly implemented memory access functionality results in a bad ratio between local and remote memory access, and causes low performance on such architectures. To address this problem, the developers of such applications rely on tools to make these kinds of performance problems visible. This work presents a new tool for the visualization of performance data of the non-uniform memory access behavior. Because of the visual design of the tool, the developer is able to judge the severity of remote memory access in a time-dependent simulation, which is currently not possible using existing tools.




Poster: Visualizing Geothermal Simulation Data with Uncertainty


Sebastian Freitag, Bernd Hentschel, Torsten Wolfgang Kuhlen, Jan Niederau, Christian Vogt, Anozie Ebigbo, Gabriele Marquart
Proceedings of the IEEE Visualization (2014)
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Simulations of geothermal reservoirs inherently contain uncertainty due to the fact that the underlying physical models are created from sparse data. Moreover, this uncertainty often cannot be completely expressed by simple key measures (e.g., mean and standard deviation), as the distribution of possible values is often not unimodal. Nevertheless, existing visualizations of these simulation data often completely neglect displaying the uncertainty, or are limited to a mean/variance representation. We present an approach to visualize geothermal simulation data that deals with both cases: scalar uncertainties as well as general ensembles of data sets. Users can interactively define two-dimensional transfer functions to visualize data and uncertainty values directly, or browse a 2D scatter plot representation to explore different possibilities in an ensemble.




Poster: Guided Tour Creation in Immersive Virtual Environments


Sebastian Pick, Andrea Bönsch, Irene Tedjo-Palczynski, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE Symposium on 3D User Interfaces (3DUI) (2014)
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Guided tours have been found to be a good approach to introducing users to previously unknown virtual environments and to allowing them access to relevant points of interest. Two important tasks during the creation of guided tours are the definition of views onto relevant information and their arrangement into an order in which they are to be visited. To allow a maximum of flexibility an interactive approach to these tasks is desirable. To this end, we present and evaluate two approaches to the mentioned interaction tasks in this paper. The first approach is a hybrid 2D/3D interaction metaphor in which a tracked tablet PC is used as a virtual digital camera that allows to specify and order views onto the scene. The second one is a purely 3D version of the first one, which does not require a tablet PC. Both approaches were compared in an initial user study, whose results indicate a superiority of the 3D over the hybrid approach.

» Show BibTeX

@InProceedings{Pick2014,
Title = {{P}oster: {G}uided {T}our {C}reation in {I}mmersive {V}irtual {E}nvironments},
Author = {Sebastian Pick and Andreas B\"{o}nsch and Irene Tedjo-Palczynski and Bernd Hentschel and Torsten Kuhlen},
Booktitle = {IEEE Symposium on 3D User Interfaces (3DUI), 2014},
Year = {2014},
Month = {March},
Pages = {151-152},
Doi = {10.1109/3DUI.2014.6798865},
Url = {http://ieeexplore.ieee.org/xpl/abstractReferences.jsp?arnumber=6798865}
}





Poster: Interactive 3D Force-Directed Edge Bundling on Clustered Edges


Daniel Zielasko, Benjamin Weyers, Bernd Hentschel, Torsten Wolfgang Kuhlen
Poster Abstracts of IEEE Symposium on Information Visualization (2014)
pubimg

Graphs play an important role in data analysis. Especially, graphs with a natural spatial embedding can benefit from a 3D visualization. But even more then in 2D, graphs visualized as intuitively readable 3D node-link diagrams can become very cluttered. This makes graph exploration and data analysis difficult. For this reason, we focus on the challenge of reducing edge clutter by utilizing edge bundling. In this paper we introduce a parallel, edge cluster based accelerator for the force-directed edge bundling algorithm presented in [Holten2009]. This opens up the possibility for user interaction during and after both the clustering and the bundling.




Interactive Definition of Discrete Color Maps for Volume Rendered Data in Immersive Virtual Environments


Claudia Hänel, Sebastian Freitag, Bernd Hentschel, Torsten Wolfgang Kuhlen
2nd International Workshop on Immersive Volumetric Interaction (WIVI 2014) at IEEE Virtual Reality (2014)
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The visual discrimination of different structures in one or multiple combined volume data sets is generally done with individual transfer functions that can usually be adapted interactively. Immersive virtual environments support the depth perception and thus the spatial orientation in these volume visualizations. However, complex 2D menus for elaborate transfer function design cannot be easily integrated. We therefore present an approach for changing the color mapping during volume exploration with direct volume interaction and an additional 3D widget. In this way we incorporate the modification of a color mapping for a large number of discretely labeled brain areas in an intuitive way into the virtual environment. We use our approach for the analysis of a patient’s data with a brain tissue degenerating disease to allow for an interactive analysis of affected regions.

» Show BibTeX

@inproceedings{Hanel2014a,
address = {Minneapolis},
author = {H{\"{a}}nel, Claudia and Freitag, Sebastian and Hentschel, Bernd and Kuhlen, Torsten},
booktitle = {2nd International Workshop on Immersive Volumetric Interaction (WIVI 2014) at IEEE Virtual Reality 2014},
editor = {Banic, Amy and O'Leary, Patrick and Laha, Bireswar},
title = {{Interactive Definition of Discrete Color Maps for Volume Rendered Data in Immersive Virtual Environments}},
year = {2014}
}





Software Phantom with Realistic Speckle Modeling for Validation of Image Analysis Methods in Echocardiography


Yuen Cheong Law Wan, Daniel Tenbrinck, Xiaoyi Jiang, Torsten Wolfgang Kuhlen
SPIE Medical Imaging - International Society for Optics and Photonics (2014)
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Computer-assisted processing and interpretation of medical ultrasound images is one of the most challenging tasks within image analysis. Physical phenomena in ultrasonographic images, e.g., the characteristic speckle noise and shadowing effects, make the majority of standard methods from image analysis non optimal. Furthermore, validation of adapted computer vision methods proves to be difficult due to missing ground truth information. There is no widely accepted software phantom in the community and existing software phantoms are not flexible enough to support the use of specific speckle models for different tissue types, e.g., muscle and fat tissue. In this work we propose an anatomical software phantom with a realistic speckle pattern simulation to fill this gap and provide a flexible tool for validation purposes in medical ultrasound image analysis. We discuss the generation of speckle patterns and perform statistical analysis of the simulated textures to obtain quantitative measures of the realism and accuracy regarding the resulting textures.




Interactive 3D Visualization of Structural Changes in the Brain of a Person With Corticobasal Syndrome


Claudia Hänel, Peter Pieperhoff, Bernd Hentschel, Katrin Amunts, Torsten Wolfgang Kuhlen
Frontiers in Neuroinformatics (2014)
pubimg

The visualization of the progression of brain tissue loss in neurodegenerative diseases like corticobasal syndrome (CBS) can provide not only information about the localization and distribution of the volume loss, but also helps to understand the course and the causes of this neurodegenerative disorder. The visualization of such medical imaging data is often based on 2D sections, because they show both internal and external structures in one image. Spatial information, however, is lost. 3D visualization of imaging data is capable to solve this problem, but it faces the difficulty that more internally located structures may be occluded by structures near the surface. Here, we present an application with two designs for the 3D visualization of the human brain to address these challenges. In the first design, brain anatomy is displayed semi-transparently; it is supplemented by an anatomical section and cortical areas for spatial orientation, and the volumetric data of volume loss. The second design is guided by the principle of importance-driven volume rendering: A direct line-of-sight to the relevant structures in the deeper parts of the brain is provided by cutting out a frustum-like piece of brain tissue. The application was developed to run in both, standard desktop environments and in immersive virtual reality environments with stereoscopic viewing for improving the depth perception. We conclude that the presented application facilitates the perception of the extent of brain degeneration with respect to its localization and affected regions.

» Show BibTeX

@article{Hanel2014b,
author = {H{\"{a}}nel, Claudia and Pieperhoff, Peter and Hentschel, Bernd and Amunts, Katrin and Kuhlen, Torsten},
issn = {1662-5196},
journal = {Frontiers in Neuroinformatics},
number = {42},
pmid = {24847243},
title = {{Interactive 3D visualization of structural changes in the brain of a person with corticobasal syndrome.}},
url = {http://journal.frontiersin.org/article/10.3389/fninf.2014.00042/abstract},
volume = {8},
year = {2014}
}





Failure Mode and Effects Analysis in Designing a Virtual Reality-Based Training Simulator for Bilateral Sagittal Split Osteotomy


Raluca Sofronia, Thomas Knott, Arjana Davidescu, Gerorg Savii, Torsten Wolfgang Kuhlen, Marcus Gerressen
International Journal of Medical Robotics and Computer Assisted Surgery (2013)
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Virtual reality-based simulators offer a cost-effective and efficient alternative to traditional medical training and planning. Developing a simulator that enables the training of medical skills and also supports recognition of errors made by the trainee is a challenge. The first step in developing such a system consists of error identification in the real procedure, in order to ensure that the training environment covers the most significant errors that can occur. This paper focuses on identifying the main system requirements for an interactive simulator for training bilateral sagittal split osteotomy (BSSO). An approach is proposed based on failure mode and effects analysis (FMEA), a risk analysis method that is well structured and already an approved technique in other domains. Based on the FMEA results, a BSSO training simulator is currently being developed, which centers upon the main critical steps of the procedure (sawing and splitting) and their main errors. FMEA seems to be a suitable tool in the design phase of developing medical simulators. Herein, it serves as a communication medium for knowledge transfer between the medical experts and the system developers. The method encourages a reflective process and allows identification of the most important elements and scenarios that need to be trained.




VisNEST – Interactive Analysis of Neural Activity Data


Christian Nowke, Maximilian Schmidt, Sacha J. Van Albada, Jochen M. Eppler, Rembrandt Bakker, Markus Diesmann, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE Symposium on Biological Data Visualization (BioVis) (2013)
pubimg

The aim of computational neuroscience is to gain insight into the dynamics and functionality of the nervous system by means of modeling and simulation. Current research leverages the power of High Performance Computing facilities to enable multi-scale simulations capturing both low-level neural activity and large-scale interactions between brain regions. In this paper, we describe an interactive analysis tool that enables neuroscientists to explore data from such simulations. One of the driving challenges behind this work is the integration of macroscopic data at the level of brain regions with microscopic simulation results, such as the activity of individual neurons. While researchers validate their findings mainly by visualizing these data in a non-interactive fashion, state-of-the-art visualizations, tailored to the scientific question yet sufficiently general to accommodate different types of models, enable such analyses to be performed more efficiently. This work describes several visualization designs, conceived in close collaboration with domain experts, for the analysis of network models. We primarily focus on the exploration of neural activity data, inspecting connectivity of brain regions and populations, and visualizing activity flux across regions. We demonstrate the effectiveness of our approach in a case study conducted with domain experts.




An Evaluation of Two Simple Methods for Representing Heaviness in Immersive Virtual Environments


Johannes Hummel, Janki Dodiya, Robin Wolff, Andreas Gerndt, Torsten Wolfgang Kuhlen
IEEE Symposium on 3D User Interfaces (3DUI) (2013)
pubimg

Weight perception in virtual environments generally can be achieved with haptic devices. However, most of these are hard to integrate in an immersive virtual environment (IVE) due to their technical complexity and the restriction of a user's movement within the IVE. We describe two simple methods using only a wireless light-weight finger-tracking device in combination with a physics simulated hand model to create a feeling of heaviness of virtual objects when interacting with them in an IVE. The first method maps the varying distance between tracked fingers and the thumb to the grasping force required for lifting a virtual object with a given weight. The second method maps the detected intensity of finger pinch during grasping gestures to the lifting force. In an experiment described in this paper we investigated the potential of the proposed methods for the discrimination of heaviness of virtual objects by finding the just noticeable difference (JND) to calculate the Weber fraction. Furthermore, the workload that users experienced using these methods was measured to gain more insight into their usefulness as interaction technique. At a hit ratio of 0.75, the determined Weber fraction using the finger distance based method was 16.25% and using the pinch based method was 15.48%, which corresponds to values found in related work. There was no significant effect of method on the difference threshold measured and the workload experienced, however the user preference was higher for the pinch based method. The results demonstrate the capability of the proposed methods for the perception of heaviness in IVEs and therefore represent a simple alternative to haptics based methods.




Research Challenges for Visualization Software


Hank Childs, Berk Geveci, Will Schroeder, Jeremy Meredith, Kenneth Moreland, Christopher Sewell, Torsten Wolfgang Kuhlen
Computer (2013)

Over the last twenty-five years, visualization software has evolved into robust frameworks that can be used for research projects, rapid prototype development, or as the basis of richly featured, end-user tools. In this article, new take stock of current capabilities and describe upcoming challenges facing visualization software in six categories: massive parallelization, emerging processor architectures, application architecture and data management,data models, rendering, and interaction. Further, for each of these categories, we describe evolutionary advances sufficient to meet the visualization software challenge, and posit areas in which revolutionary advances are required




Virtual Air Traffic System Simulation - Aiding the Communication of Air Traffic Effects


Sebastian Pick, Frank Wefers, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE Virtual Reality (VR) (2013)
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A key aspect of air traffic infrastructure projects is the communication between stakeholders during the approval process regarding their environmental impact. Yet, established means of communication have been found to be rather incomprehensible. In this paper we present an application that addresses these communication issues by enabling the exploration of airplane noise emissions in the vicinity of airports in a virtual environment (VE). The VE is composed of a model of the airport area and flight movement data. We combine a real-time 3D auralization approach with visualization techniques to allow for an intuitive access to noise emissions. Specifically designed interaction techniques help users to easily explore and compare air traffic scenarios.




Extended Pie Menus for Immersive Virtual Environments


Sascha Gebhardt, Sebastian Pick, Franziska Leithold, Bernd Hentschel, Torsten Wolfgang Kuhlen
IEEE Transactions on Visualization and Computer Graphics (2013)

Pie menus are a well-known technique for interacting with 2D environments and so far a large body of research documents their usage and optimizations. Yet, comparatively little research has been done on the usability of pie menus in immersive virtual environments (IVEs). In this paper we reduce this gap by presenting an implementation and evaluation of an extended hierarchical pie menu system for IVEs that can be operated with a six-degrees-of-freedom input device. Following an iterative development process, we first developed and evaluated a basic hierarchical pie menu system. To better understand how pie menus should be operated in IVEs, we tested this system in a pilot user study with 24 participants and focus on item selection. Regarding the results of the study, the system was tweaked and elements like check boxes, sliders, and color map editors were added to provide extended functionality. An expert review with five experts was performed with the extended pie menus being integrated into an existing VR application to identify potential design issues. Overall results indicated high performance and efficient design.




Poster: Interactive Visualization of Brain-Scale Spiking Activity


Christian Nowke, Bernd Hentschel, Torsten Wolfgang Kuhlen, Maximilian Schmidt, Sacha J. Van Albada, Jochen M. Eppler, Rembrandt Bakker, Markus Diesmann
BMC Neuroscience
pubimg

In recent years, the simulation of spiking neural networks has advanced in terms of both simulation technology and knowledge about neuroanatomy. Due to these advances, it is now possible to run simulations at the brain scale, which produce an unprecedented amount of data to be analyzed and understood by researchers. As aid, VisNEST, a tool for the combined visualization of simulated spike data and anatomy was developed.




Adaptive Human Motion Prediction using Multiple Model Approaches


Markus Joppich, Dominik Rausch, Torsten Wolfgang Kuhlen
Virtuelle und Erweiterte Realität : 10. Workshop der GI-Fachgruppe VR/AR (2013)
pubimg

A common problem in Virtual Reality is latency. Especially for head tracking, latency can lead to a lower immersion. Prediction can be used to reduce the effect of latency. However, for good results the prediction process has to be reliably fast and accurate. Human motion is not homogeneous and humans often tend to change the way they move. Prediction models can be designed for these special motion types. To combine the special models, a multiple model approach is presented. It constantly evaluates the quality of the different specialized motion prediction and adjusts the set of motion models. We propose two variants, and compare them to a reference prediction algorithm.




Poster Interactive Visualization of Brain Volume Changes


Claudia Hänel, Bernd Hentschel, Torsten Wolfgang Kuhlen, Peter Pieperhoff, Katrin Amunts
Proceedings of the IEEE Visualization (2013)
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The visual analysis of brain volume data by neuroscientists is commonly done in 2D coronal, sagittal and transversal views, limiting the visualization domain from potentially three to two dimensions. This is done to avoid occlusion and thus gain necessary context information. In contrast, this work intends to benefit from all spatial information that can help to understand the original data. Example data of a patient with brain degeneration are used to demonstrate how to enrich 2D with 3D data. To this end, two approaches are presented. First, a conventional 2D section in combination with transparent brain anatomy is used. Second, the principle of importance-driven volume rendering is adapted to allow a direct line-of-sight to relevant structures by means of a frustum-like cutout.




Poster: Hyperslice Visualization of Metamodels for Manufacturing Processes


Sascha Gebhardt, Bernd Hentschel, Torsten Wolfgang Kuhlen, Toufik Al Khawli, Wolfgang Schulz
Proceedings of the IEEE Visualization (2013)

In modeling and simulation of manufacturing processes, complex models are used to examine and understand the behavior and properties of the product or process. To save computation time, global approximation models, often referred to as metamodels, serve as surrogates for the original complex models. Such metamodels are difficult to interpret, because they usually have multi-dimensional input and output domains. We propose a hyperslice-based visualization approach, that uses hyperslices in combination with direct volume rendering, training point visualization, and gradient trajectory navigation, that helps in understanding such metamodels. Great care was taken to provide a high level of interactivity for the exploration of the data space.




Physically Based Rendering of the Martian Atmosphere


Peter Collienne, Robin Wolff, Andreas Gerndt, Torsten Wolfgang Kuhlen
Virtuelle und Erweiterte Realität, 10. Workshop der GI-Fachgruppe VR/AR (2013)
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With the introduction of complex precomputed scattering tables by Bruneton in 2008, the quality of visualizing atmospheric scattering vastly improved. The presented algorithms allowed for the rendering of complex atmospheric features such as multiple-scattering or light shafts in real-time and at interactive framerates. While their published implementation corresponding to the publication was merely a proof of concept, we present a more practical approach by applying their scattering theory to an already existing planetary rendering engine. Because the commonly used set of parameters only describes the atmosphere of the Earth, we further extend the scattering formulation to visualize the atmosphere of the planet Mars. Validating the modified scattering and resulting parameters is then done by comparison with available imagery from the Martian atmosphere



Comparing Auditory and Haptic Feedback for a Virtual Drilling Task


Dominik Rausch, Lukas Aspöck, Thomas Knott, Sönke Pelzer, Michael Vorländer, Torsten Wolfgang Kuhlen
Joint Virtual Reality Conference of ICAT - EGVE - EuroVR, 2012
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While visual feedback is dominant in Virtual Environments, the use of other modalities like haptics and acoustics can enhance believability, immersion, and interaction performance. Haptic feedback is especially helpful for many interaction tasks like working with medical or precision tools. However, unlike visual and auditory feedback, haptic reproduction is often difficult to achieve due to hardware limitations. This article describes a user study to examine how auditory feedback can be used to substitute haptic feedback when interacting with a vibrating tool. Participants remove some target material with a round-headed drill while avoiding damage to the underlying surface. In the experiment, varying combinations of surface force feedback, vibration feedback, and auditory feedback are used. We describe the design of the user study and present the results, which show that auditory feedback can compensate the lack of haptic feedback.

» Show BibTeX

@inproceedings {EGVE:JVRC12:049-056,
booktitle = {Joint Virtual Reality Conference of ICAT - EGVE - EuroVR},
editor = {Ronan Boulic and Carolina Cruz-Neira and Kiyoshi Kiyokawa and David Roberts},
title = {{Comparing Auditory and Haptic Feedback for a Virtual Drilling Task}},
author = {Rausch, Dominik and Aspöck, Lukas and Knott, Thomas and Pelzer, Sönke and Vorländer, Michael and Kuhlen, Torsten},
year = {2012},
publisher = {The Eurographics Association},
ISSN = {1727-530X},
ISBN = {978-3-905674-40-8},
DOI = {10.2312/EGVE/JVRC12/049-056}
pages= { -- }
}





Geometrical-Acoustics-based Ultrasound Image Simulation


Yuen Cheong Law Wan, Thomas Knott, Bernd Hentschel, Torsten Wolfgang Kuhlen
Eurographics Workshop on Visual Computing for Biology and Medicine (2012)
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Brightness modulation (B-Mode) ultrasound (US) images are used to visualize internal body structures during diagnostic and invasive procedures, such as needle insertion for Regional Anesthesia. Due to patient availability and health risks-during invasive procedures-training is often limited, thus, medical training simulators become a viable solution to the problem. Simulation of ultrasound images for medical training requires not only an acceptable level of realism but also interactive rendering times in order to be effective. To address these challenges, we present a generative method for simulating B-Mode ultrasound images using surface representations of the body structures and geometrical acoustics to model sound propagation and its interaction within soft tissue. Furthermore, physical models for backscattered, reflected and transmitted energies as well as for the beam profile are used in order to improve realism. Through the proposed methodology we are able to simulate, in real-time, plausible view- and depth-dependent visual artifacts that are characteristic in B-Mode US images, achieving both, realism and interactivity.




Poster: VisNEST - Interactive Analysis of Neural Activity Data


Christian Nowke, Bernd Hentschel, Torsten Wolfgang Kuhlen, Jochen M. Eppler, Sacha J. Van Albada, Maximilian Schmidt, Rembrandt Bakker, Markus Diesmann
Proceedings of the IEEE Visualization (2012)
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Modeling and simulating a brain’s connectivity produces an immense amount of data, which has to be analyzed in a timely fashion. Neuroscientists are currently modeling parts of the brain – e.g. the visual cortex – of primates like Macaque monkeys in order to deduce functionality and transfer newly gained insights to the human brain. Current research leverages the power of today’s High Performance Computing (HPC) machines in order to simulate low level neural activity. In this paper, we describe an interactive analysis tool that enables neuroscientists to visualize the resulting simulation output. One of the driving challenges behind our development is the integration of macroscopic data, e.g. brain areas, with microscopic simulation results, e.g. spiking behavior of individual neurons.

Honorable Mention!




CAVIR: Correspondence Analysis in Virtual Reality. Ways to a Valid Interpretation of Correspondence Analytical Point Clouds in Virtual Environments


Frederik Graff, Andrea Bönsch, Daniel Bündgens, Torsten Wolfgang Kuhlen
International Masaryk Conference for Ph.D. Students and Young Researchers (2012)
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Correspondence Analysis (CA) is frequently used to interpret correlations between categorical variables in the area of market research. To do so, coherences of variables are converted to a three-dimensional point cloud and plotted as three different 2D-mappings. The major challenge is to correctly interpret these plottings. Due to a missing axis, distances can easily be under- or overestimated. This can lead to a misclustering and misinterpretation of data and thus to faulty conclusions. To address this problem we present CAVIR, an approach for CA in Virtual Reality. It supports users with a virtual three-dimensional representation of the point cloud and different options to show additional information, to measure Euclidean distances, and to cluster points. Besides, the free rotation of the entire point cloud enables the CA user to always have a correct view of the data.

» Show BibTeX

@Article{Graff2012,
Title = {{CAVIR}: {C}orrespondence {A}nalysis in {V}irtual {R}eality. {W}ays to a {V}alid {I}nterpretation of {C}orrespondence {A}nalytical {P}oint {C}louds in {V}irtual {E}nvironments},
Author = {Frederik Graff and Andrea B\"{o}nsch and Daniel B\"{u}ndgens and Torsten Kuhlen},
Journal = {{C}onference {P}roceedings: {I}nternational {M}asaryk {C}onference for {P}h.{D}. {S}tudents and {Y}oung {R}esearchers},
Year = {2012},
Pages = {653-662},
Volume = {3},
Url = {http://www.vedeckekonference.cz/library/proceedings/mmk_2012.pdf}
}





CAVIR: Correspondence Analysis in Virtual Reality


Andrea Bönsch, Frederik Graff, Daniel Bündgens, Torsten Wolfgang Kuhlen
Virtuelle und Erweiterte Realität, 9. Workshop der GI-Fachgruppe VR/AR (2012)
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Correspondence Analysis (CA) is used to interpret correlations between categorical variables in the areas of social science and market research. To do so, coherences of variables are converted to a three-dimensional point cloud and plotted as several different 2D-mappings, each containing two axes. The major challenge is to correctly interpret these plottings. Due to a missing axis, distances can easily be under- or overestimated. This can lead to a misinterpretation and thus a misclustering of data. To address this problem we present CAVIR, an approach for CA in Virtual Reality. It supports users with a three-dimensional representation of the point cloud and different options to show additional information, to measure Euclidean distances, and to cluster points. Besides, the motion parallax and a free rotation of the entire point cloud enable the CA expert to always have a correct view of the data.

Best Presentation Award!

» Show BibTeX

@Article{Boensch2012,
Title = {{CAVIR}: {C}orrespondence {A}nalysis in {V}irtual {R}eality},
Author = {Andrea B\"{o}nsch and Frederik Graff and Daniel B\"{u}ndgens and Torsten Kuhlen},
Journal = {{V}irtuelle und {E}rweiterte {R}ealit\"at, 9. {W}orkshop der {GI}-{F}achgruppe {VR}/{AR}},
Year = {2012},
Pages = {49-60},
ISSN = {978-3-8440-1309-2}
Publisher = {Shaker Verlag},
}





Visualizing Acoustical Simulation Data in Immersive Virtual Environments


Sebastian Freitag, Dominik Rausch, Torsten Wolfgang Kuhlen
Virtuelle und Erweiterte Realität: 8. Workshop der GI-Fachgruppe VR/AR (2011)
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In this contribution, we present an immersive visualization of room acoustical simulation data. In contrast to the commonly employed external viewpoint, our approach places the user inside the visualized data. The main problem with this technique is the occlusion of some data points by others. We present different solutions for this problem that allow an interactive analysis of the simulation data.




Bimanual Haptic Simulator for Medical Training: System Architecture and Performance Measurements


Sebastian Ullrich, Dominik Rausch, Torsten Wolfgang Kuhlen
Joint Virtual Reality Conference of EGVE - EuroVR, 2011
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In this paper we present a simulator for two-handed haptic interaction. As an application example, we chose a medical scenario that requires simultaneous interaction with a hand and a needle on a simulated patient. The system combines bimanual haptic interaction with a physics-based soft tissue simulation. To our knowledge the combination of finite element methods for the simulation of deformable objects with haptic rendering is seldom addressed, especially with two haptic devices in a non-trivial scenario. Challenges are to find a balance between real-time constraints and high computational demands for fidelity in simulation and to synchronize data between system components. The system has been successfully implemented and tested on two different hardware platforms: one mobile on a laptop and another stationary on a semi-immersive VR system. These two platforms have been chosen to demonstrate scaleability in terms of fidelity and costs. To compare performance and estimate latency, we measured timings of update loops and logged event-based timings of several components in the software.

» Show BibTeX

@inproceedings {EGVE:JVRC11:039-046,
booktitle = {Joint Virtual Reality Conference of EGVE - EuroVR},
editor = {Sabine Coquillart and Anthony Steed and Greg Welch},
title = {{Bimanual Haptic Simulator for Medical Training: System Architecture and Performance Measurements}},
author = {Ullrich, Sebastian and Rausch, Dominik and Kuhlen, Torsten},
year = {2011},
pages={39--46},
publisher = {The Eurographics Association},
DOI = {10.2312/EGVE/JVRC11/039-046}
}





Effciently Navigating Data Sets Using the Hierarchy Browser


Andrea Bönsch, Sebastian Pick, Bernd Hentschel, Torsten Wolfgang Kuhlen
Virtuelle und Erweiterte Realität, 8. Workshop der GI-Fachgruppe VR/AR (2011)
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A major challenge in Virtual Reality is to enable users to efficiently explore virtual environments, regardless of prior knowledge. This is particularly true for complex virtual scenes containing a huge amount of potential areas of interest. Providing the user convenient access to these areas is of prime importance, just like supporting her to orient herself in the virtual scene. There exist techniques for either aspect, but combining these techniques into one holistic system is not trivial. To address this issue, we present the Hierarchy Browser. It supports the user in creating a mental image of the scene. This is done by offering a well-arranged, hierarchical visual representation of the scene structure as well as interaction techniques to browse it. Additional interaction allows to trigger a scene manipulation, e.g. an automated travel to a desired area of interest. We evaluate the Hierarchy Browser by means of an expert walkthrough.

» Show BibTeX

@Article{Boensch2011,
Title = {{E}fficiently {N}avigating {D}ata {S}ets {U}sing the {H}ierarchy {B}rowser},
Author = {Andrea B\"{o}nsch and Sebastian Pick and Bernd Hentschel and Torsten Kuhlen},
Journal = {{V}irtuelle und {E}rweiterte {R}ealit\"at, 8. {W}orkshop der {GI}-{F}achgruppe {VR}/{AR}},
Year = {2011},
Pages = {37-48},
ISSN = {978-3-8440-0394-9}
Publisher = {Shaker Verlag}
}





Efficient Rasterization for Outdoor Radio Wave Propagation


Arne Schmitz , Tobias Rick, Thomas Karolski, Torsten Wolfgang Kuhlen, Leif Kobbelt
IEEE Transactions on Visualization and Computer Graphics, Feb. 2011, Vol. 17, Issue 2, pp. 159 - 170
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Conventional beam tracing can be used for solving global illumination problems. It is an efficient algorithm, and performs very well when implemented on the GPU. This allows us to apply the algorithm in a novel way to the problem of radio wave propagation. The simulation of radio waves is conceptually analogous to the problem of light transport. We use a custom, parallel rasterization pipeline for creation and evaluation of the beams. We implement a subset of a standard 3D rasterization pipeline entirely on the GPU, supporting 2D and 3D framebuffers for output. Our algorithm can provide a detailed description of complex radio channel characteristics like propagation losses and the spread of arriving signals over time (delay spread). Those are essential for the planning of communication systems required by mobile network operators. For validation, we compare our simulation results with measurements from a real world network. Furthermore, we account for characteristics of different propagation environments and estimate the influence of unknown components like traffic or vegetation by adapting model parameters to measurements.




3D Sketch Recognition for Interaction in Virtual Environments


Dominik Rausch, Ingo Assenmacher, Torsten Wolfgang Kuhlen
Workshop in Virtual Reality Interactions and Physical Simulation (VRIPHYS), 2010
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We present a comprehensive 3D sketch recognition framework for interaction within Virtual Environments that allows to trigger commands by drawing symbols, which are recognized by a multi-level analysis. It proceeds in three steps: The segmentation partitions each input line into meaningful segments, which are then recognized as a primitive shape, and finally analyzed as a whole sketch by a symbol matching step. The whole framework is configurable over well-defined interfaces, utilizing a fuzzy logic algorithm for primitive shape learning and a textual description language to define compound symbols. It allows an individualized interaction approach that can be used without much training and provides a good balance between abstraction and intuition. We show the real-time applicability of our approach by performance measurements.

» Show BibTeX

@inproceedings {PE:vriphys:vriphys10:115-124,
booktitle = {Workshop in Virtual Reality Interactions and Physical Simulation "VRIPHYS" (2010)},
editor = {Kenny Erleben and Jan Bender and Matthias Teschner},
title = {{3D} Sketch Recognition for Interaction in Virtual Environments},
author = {Rausch, Dominik and Assenmacher, Ingo and Kuhlen, Torsten},
year = {2010},
publisher = {The Eurographics Association},
DOI = {10.2312/PE/vriphys/vriphys10/115-124}
}





Virtual Reality System at RWTH Aachen University


Frank Wefers, Sönke Pelzer, Dominik Rausch, Michael Vorländer, Torsten Wolfgang Kuhlen
Proceedings of the International Symposium on Room Acoustics (ISRA), 2010
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During the last decade, Virtual Reality (VR) systems have progressed from primary laboratory experiments into serious and valuable tools. Thereby, the amount of useful applications has grown in a large scale, covering conventional use, e.g., in science, design, medicine and engineering, as well as more visionary applications such as creating virtual spaces that aim to act real. However, the high capabilities of today’s virtual reality systems are mostly limited to firstclass visual rendering, which directly disqualifies them for immersive applications. For general application, though, VR-systems should feature more than one modality in order to boost its range of applications. The CAVE-like immersive environment that is run at RWTH Aachen University comprises state-of-the-art visualization and auralization with almost no constraints on user interaction. In this article a summary of the concept, the features and the performance of our VR-system is given. The system features a 3D sketching interface that allows controlling the application in a very natural way by simple gestures. The sound rendering engine relies on present-day knowledge of Virtual Acoustics and enables a physically accurate simulation of sound propagation in complex environments, including important wave effects such as sound scattering, airborne sound insulation between rooms and sound diffraction. In spite of this realistic sound field rendering, not only spatially distributed and freely movable sound sources and receivers are supported, but also modifications and manipulations of the environment itself. The auralization concept is founded on pure FIR filtering which is realized by highly parallelized non-uniformly partitioned convolutions. A dynamic crosstalk cancellation system performs the sound reproduction that delivers binaural signals to the user without the need of headphones. The significant computational complexity is handled by distributed computation on PCclusters that drive the simulation in real-time even for huge audio-visual scenarios.

» Show BibTeX

@inproceedings{schroder2010virtual,
title={Virtual reality system at RWTH Aachen University},
author={Schr{\"o}der, Dirk and Wefers, Frank and Pelzer, S{\"o}nke and Rausch, Dominik and Vorl{\"a}nder, Michael and Kuhlen, Torsten},
booktitle={Proceedings of the international symposium on room acoustics (ISRA), Melbourne, Australia},
year={2010}
}





Simulation of Radio Wave Propagation by Beam Tracing


Arne Schmitz , Tobias Rick, Thomas Karolski, Leif Kobbelt, Torsten Wolfgang Kuhlen
Eurographics Symposium on Parallel Graphics and Visualization
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Beam tracing can be used for solving global illumination problems. It is an efficient algorithm, and performs very well when implemented on the GPU. This allows us to apply the algorithm in a novel way to the problem of radio wave propagation. The simulation of radio waves is conceptually analogous to the problem of light transport. However, their wavelengths are of proportions similar to that of the environment. At such frequencies, waves that bend around corners due to diffraction are becoming an important propagation effect. In this paper we present a method which integrates diffraction, on top of the usual effects related to global illumination like reflection, into our beam tracing algorithm. We use a custom, parallel rasterization pipeline for creation and evaluation of the beams. Our algorithm can provide a detailed description of complex radio channel characteristics like propagation losses and the spread of arriving signals over time (delay spread). Those are essential for the planning of communication systems required by mobile network operators. For validation, we compare our simulation results with measurements from a real world network.




Beam Tracing for Multipath Propagation in Urban Environments


Arne Schmitz , Tobias Rick, Thomas Karolski, Leif Kobbelt, Torsten Wolfgang Kuhlen
3rd European Conference on Antennas and Propagation, to appear
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We present a novel method for efficient computation of complex channel characteristics due to multipath effects in urban microcell environments. Significant speedups are obtained compared to state-of-the-art ray-tracing algorithms by tracing continuous beams and by using parallelization techniques. We optimize simulation parameters using on-site measurements from real world networks. We formulate the adaption of model parameters as a constrained least-squares problem where each row of the matrix corresponds to one measurement location, and where the columns are formed by the beams that reach the respective location.




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