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apgv 2009: symposium on applied perception in graphics and visualization

作者： Steinicke, Frank Bruder, Gerd Hinrichs, Klaus Lappe, Markus Ries, Brian Interrante, Victoria Visualization and Computer Graphics Research Group Germany Psychology Department II University of Münster Germany Department of Computer Science and Engineering University of Minnesota United States

ISBN: (纸本)9781605587431

Several experiments have provided evidence that ego-centric distances are perceived as compressed in immersive virtual environments relative to the real world. The principal factors responsible for this phenomenon have remained largely unknown. However, recent experiments suggest that when the virtual environment (VE) is an exact replica of a user's real physical surroundings, the person's distance perception improves. Furthermore, it has been shown that when users start their virtual reality (VR) experience in such a virtual replica and then gradually transition to a different VE, their sense of presence in the actual virtual world increases significantly. In this case the virtual replica serves as a transitional environment between the real and virtual world. In this paper we examine whether a person's distance estimation skills can be transferred from a transitional environment to a different VE. We have conducted blind walking experiments to analyze if starting the VR experience in a transitional environment can improve a person's ability to estimate distances in an immersive VR system. We found that users significantly improve their distance estimation skills when they enter the virtual world via a transitional environment. © 2009 ACM.

关键词： Virtual reality

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A schema-based selective rendering framework 09

A schema-based selective rendering framework

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apgv 2009: symposium on applied perception in graphics and visualization

作者： Zotos, Alexandros Mania, Katerina Mourkoussis, Nicholaos Technical University of Crete Greece University of Sussex United Kingdom

ISBN: (纸本)9781605587431

perception principles have been incorporated into rendering algorithms in order to optimize rendering computation and produce photorealistic images from a human rather than a machine point of view. In order to economize on rendering computation, selective rendering guides high level of detail to specific regions of a synthetic scene and lower quality to the remaining scene, without compromising the level of information transmitted. Scene regions that have been rendered in low and high quality can be combined to form one complete scene. Such decisions are guided by predictive attention modeling, gaze or task-based information. We propose a novel selective rendering approach which is task and gaze-independent, simulating cognitive creation of spatial hypotheses. Scene objects are rendered in varying polygon quality according to how they are associated with the context (schema) of the scene. Experimental studies in synthetic scenes have revealed that consistent objects which are expected to be found in a scene can be rendered in lower quality without affecting information uptake. Exploiting such expectations, inconsistent items which are salient require a high level of rendering detail in order for them to be perceptually acknowledged. The contribution of this paper is an innovative x3D-based selective rendering framework based on memory schemas and implemented through metadata enrichment. © 2009 ACM.

关键词： Rendering (computer graphics)

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Distance perception in NPR immersive virtual environments, revisited 09

Distance perception in NPR immersive virtual environments, r...

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apgv 2009: symposium on applied perception in graphics and visualization

作者： Phillips, Lane Ries, Brian Interrante, Victoria Kaeding, Michael Anderson, Lee Department of Computer Science University of Minnesota United States Department of Architecture University of Minnesota United States

ISBN: (纸本)9781605587431

Non-photorealistic rendering (NPR) is a representational technique that allows communicating the essence of a design while giving the viewer the sense that the design is open to change. Our research aims to address the question of how to effectively use non-photorealistic rendering in immersive virtual environments to enable the intuitive exploration of early architectural design concepts at full scale. Previous studies have shown that people typically underestimate egocentric distances in immersive virtual environments, regardless of rendering style, although we have recently found that distance estimation errors are minimized in the special case that the virtual environment is a high-fidelity replica of a real environment that the viewer is presently in or has recently been in. In this paper we re-examine the impact of rendering style on distance perception accuracy in this virtual environments context. Specifically, we report the results of an experiment that seeks to assess the accuracy with which people judge distances in a non-photorealistically rendered virtual environment that is a directly-derived stylistic abstraction of the actual environment that they are currently in. Our results indicate that people tend to underestimate distances to a significantly greater extent in a co-located virtual environment when it is rendered using a line-drawing style than when it is rendered using high fidelity textures derived from photographs. © 2009 ACM.

关键词： Virtual reality

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Display size does not affect egocentric distance perception of naturalistic stimuli 09

Display size does not affect egocentric distance perception ...

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apgv 2009: symposium on applied perception in graphics and visualization

作者： Riecke, Bernhard E. Behbahani, Pooya Amini Shaw, Chris D. Simon Fraser University Canada

ISBN: (纸本)9781605587431

Although people are quite accurate in visually perceiving absolute egocentric distances in real environments up to 20m, they usually underestimate distances in virtual environments presented through head-mounted displays (HMDs). Several previous studies examined different potential factors, but none of these factors could convincingly explain the observed distance compressionin HMDs. In this study, we investigated the potential influence of naturalistic stimulus presentation and display size - a factor largely overlooked in previous studies. To this end, we used an indirect blindfolded walking task to previously-seen targets. Participants viewed photos of targets located at various distances on the ground through different-sized displays (HMD, 24" monitor, and 50" screen) and walked without vision to where they thought the location of the target was. Real-world photographs were used to avoid potential artifacts of computer-graphics stimuli. Displays were positioned to provide identical fields of view (32 × 24). Distance judgments were unexpectedly highly accurate and showed no signs of distance compression for any of the displays. Moreover, display size did not affect distance perception, and performance was virtually identical to a real world baseline, where real-world targets were viewed through 32 × 24 field of view restrictors. A careful analysis of potential underlying factors suggests that the typicallyobserved distance compression for HMDs might be overcome by using naturalistic real-world stimuli. This might also explain why display size did not affect distance judgments. © 2009 ACM.

关键词： Virtual reality

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Effects of scale change on distance perception in virtual environments 09

Effects of scale change on distance perception in virtual en...

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apgv 2009: symposium on applied perception in graphics and visualization

作者： Nguyen, Tien Dat Ziemer, Christine J. Plumert, Jodie M. Cremer, James F. Kearney, Joseph K. Computer Science Department University of Iowa United States Department of Psychology University of Iowa United States

ISBN: (纸本)9781605587431

We conducted two experiments to investigate effects of scale changes on distance perception in virtual environments. In both experiments, participants first made distance estimates with feedback in a virtual tunnel (adaptation) and then made distance estimates without feedback in a differently sized environment (test). We examined two types of scale changes. In the "Tunnel Scaled" conditions, only the size of the tunnel changed from adaptation to test. In the "All Scaled" conditions, both the tunnel and target sizes changed from adaptation to test, along with the distance between the targets. Both experiments were carried out in an HMD. In the first experiment, participants made distance estimates by moving to targets via a joystick. In the "All Scaled" condition, participants overshot relative to adaptation when going from a large to a small environment, and they undershot relative to adaptation when going from a small to a large environment. We found almost no effects of scale change in either direction when only the tunnel was scaled at test. Experiment 2 was the same except that subjects made distance estimates via blindfolded walking. The pattern of results was the same, though the size of the overshoot/undershoot was attenuated. The discussion focuses on explanations for the effects of scale changes on distance estimates. © 2009 ACM.

关键词： Virtual reality

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Step synchronization and third person speed perception in virtual environment locomotion simulators 09

Step synchronization and third person speed perception in vi...

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apgv 2009: symposium on applied perception in graphics and visualization

作者： Lehtinen, Sonja Cheung, Clara Pelah, Adar Cameron, Jonathan Lasenby, Joan University of Cambridge United Kingdom University of York United Kingdom

ISBN: (纸本)9781605587431

Human locomotion is known to be influenced by observation of another person's gait. For example, athletes often synchronize their step in long distance races. However, how interaction with a virtual runner affects the gait of a real runner has not been studied. We investigated this by creating an illusion of running behind a virtual model (VM) using a treadmill and large screen virtual environment showing a video of a VM. We looked at step synchronization between the real and virtual runner and at the role of the step frequency (SF) in the real runner's perception of VM speed. We found that subjects match VM SF when asked to match VM speed with their own (Figure 1). This indicates step synchronization may be a strategy of speed matching or speed perception. Subjects chose higher speeds when VMSF was higher (though VM was 12km/h in all videos). This effect was more pronounced when the speed estimate was rated verbally while standing still. (Figure 2). This may due to correlated physical activity affecting the perception of VM speed [Jacobs et al. 2005];or step synchronization altering the subjects' perception of self speed [Durgin et al. 2007]. Our findings indicate that third person activity in a collaborative virtual locomotive environment can have a pronounced effect on an observer's gait activity and their perceptual judgments of the activity of others: the SF of others (virtual or real) can potentially influence one's perception of self speed and lead to changes in speed and SF. A better understanding of the underlying mechanisms would support the design of more compelling virtual trainers and may be instructive for competitive athletics in the real world. © 2009 ACM.

关键词： Virtual reality

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Effects of animation, user-controlled interactions, and multiple static views in understanding 3D structures 09

Effects of animation, user-controlled interactions, and mult...

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apgv 2009: symposium on applied perception in graphics and visualization

作者： Sando, Taylor Tory, Melanie Irani, Pourang University of Manitoba Canada University of Victoria Canada

ISBN: (纸本)9781605587431

visualizations of 3D spatial structures use various techniques such as user controlled interactions or 2D projection views to convey the structure to users. Researchers have shown that motion cues can help assimilate the structure of 3D spatial data, particularly for discerning occluded parts of the objects. However, motion cues or smooth animations also have costs - they increase the viewing time. What remains unclear is whether any one particular viewing modality allows users to understand and operate on the 3D structure as effectively as a combination of 2D and 3D static views. To assess the effectiveness of understanding 3D structures, we carried out three experiments. In all three experiments we evaluated the effectiveness of perceiving 3D structures with either self controlled interactions, animated transitions, and 2D+3D static views. In the first experiment, subjects were given a task to estimate the relative distances of objects in a 3D scene. In the second experiment, subjects made judgements to discern and identify the existence of differences between 3D objects. In the third experiment, participants were required to reconstruct a 3D spatial structure based on the 3D models presented to them. Results of the three experiments reveal that participants were more accurate and performed the spatial tasks faster with smooth animations and self-controlled interactions than with 2D+3D static views. Our results overall suggest that the costs involved in interacting or animating a 3D spatial structure are significantly outweighed by the perceptual benefits derived from viewing and interacting in these modes of presentation. © 2009 ACM.

关键词： Three dimensional computer graphics

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visualization of Signal Transduction Processes in the Crowded Environment of the Cell

Visualization of Signal Transduction Processes in the Crowde...

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IEEE Pacific visualization symposium

作者： Falk, Martin Klann, Michael Reuss, Matthias Ertl, Thomas Univ Stuttgart VISUS Visualizat Res Ctr D-7000 Stuttgart Germany Univ Stuttgart Ctr Syst Biol Inst Biochem Engn D-7000 Stuttgart Germany

ISBN: (纸本)9781424444045

In this paper, we propose a stochastic simulation to model and analyze cellular signal transduction. The high number of objects in a simulation requires advanced visualization techniques: first to handle the large data sets, second to Support the human perception in the crowded environment, and third to provide an interactive exploration tool. To adjust the state of the cell to ail external signal, a specific set of signaling molecules transports the information to the nucleus deep inside the cell. There, key molecules regulate gene expression. Ill contrast to continuous ODE models we model all signaling molecules individually in a more realistic crowded and disordered environment. Beyond spatiotemporal concentration profiles our data describes the process on a mesoscopic, molecular level, allowing a detailed view of intracellular events. In Our proposed schematic visualization individual molecules, their tracks, or reactions can be selected and brought into focus to highlight the signal transduction pathway. Segmentation, depth cues and depth of field are applied to reduce the visual complexity. We also provide a virtual microscope to display images for comparison with wet lab experiments. The method is applied to distinguish different transport modes of MAPK (mitogen-activated protein kinase) signaling molecules in a cell. In addition, we simulate the diffusion of drug molecules through the extracellular space of a solid tumor and visualize the challenges in cancer related therapeutic drug delivery.

关键词： 1.3.3 [Computer graphics]: Picture/Image Generation 1.3.7 [Computer graphics]: Three-Dimensional graphics and Realism 1.3.8 [Computer graphics]: Applications 1.6.8 [Simulation and Modeling]: Types of Simulation-Discrete Event J.3 [Life and Medical Sciences]: Biology and Genetics

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Guest editorial: Special issue on applied perception in graphics and visualization (apgv07)

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Transactions on applied perception 2009年第4期5卷 1页

作者： Fleming, Roland Langer, Michael Max Planck Institute for Biological Cybernetics McGill University

No abstract available.

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Illuminated 3D Scatterplots

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COMPUTER graphics FORUM 2009年第3期28卷 751-758页

作者： Sanftmann, Harald Weiskopf, Daniel Univ Stuttgart VISUS D-7000 Stuttgart Germany

In contrast to 2D scatterplots, the existing 3D variants have the advantage of showing one additional data dimension, but suffer from inadequate spatial and shape perception and therefore are not well suited to display structures of the underlying data. We improve shape perception by, applying a new illumination technique to the pointcloud representation of 3D scatterplots. Points are classified as locally, linear, planar, and volumetric structures-according to the eigenvalues of the inverse distance-weighted covariance matrix at each data element. Based on this classification, different lighting models are applied: codimension-2 illumination, surface illumination, and emissive volumetric illumination. Our technique lends itself to efficient GPU point rendering and can be combined with existing methods like semi-transparent rendering, halos, and depth or attribute based color coding. The user can interactively navigate in the dataset and manipulate the classification and other visualization parameters. We demonstrate our visualization technique by showing examples of multi-dimensional data and of generic pointcloud data.

关键词： I.3.7 [Computer graphics]: Three-Dimensional graphics and Realism Color, shading, shadowing, and texture

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