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3rd symposium on applied perception in graphics and visualization, APGV 2006

作者： Mourant, Ronald R. Ahmad, Najla Adetiloye, Charles Jaeger, Beverly K. Virtual Environments Laboratory Northeastern University

ISBN: (纸本)1595934294

In a simulated driving scenario, we investigated the production of vehicle velocity at 30 and 60 mph while varying the amount of optical flow (roadside trees versus no trees) and the geometric field of view (25, 55, and 85 horizontal degrees). Participant drivers were significantly less accurate in producing vehicle velocities of 30 mph as contrasted with those of the 60 mph target set. On average, the produced velocities were overestimated by 20 mph for the 30 mph target set. This may be due to an inability of driving simulators to produce authentic optical flows when traversing at 30 mph or lower velocities. Copyright © 2006 by the Association for Computing Machinery, Inc.

关键词： Sensory perception

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Enhancing interactive particle visualization with advanced shading models 06

Enhancing interactive particle visualization with advanced s...

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3rd symposium on applied perception in graphics and visualization, APGV 2006

作者： Gribble, Christiaan P. Parker, Steven G. Scientific Computing and Imaging Institute School of Computing University of Utah

ISBN: (纸本)1595934294

Particle-based simulation methods are used to model a wide range of complex phenomena and to solve time-dependent problems of various scales. Effective visualization of the resulting state should communicate subtle changes in the three-dimensional structure, spatial organization, and qualitative trends within a simulation as it evolves. We take steps toward understanding and using advanced shading models in the context of interactive particle visualization. Specifically, the impact of ambient occlusion and physically based diffuse interreflection is investigated using a formal user study. We find that these shading models provide additional visual cues that enable viewers to better understand subtle features within particle datasets. We also describe a visualization process that enables interactive navigation and exploration of large particle datasets, rendered with illumination effects from advanced shading models. Informal feedback from application scientists indicates that the results of this process enhance the data analysis tasks necessary for understanding complex particle datasets. Copyright © 2006 by the Association for Computing Machinery, Inc.

关键词： Enhanced recovery

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Color perception of 3D objects: Constancy with respect to variation of surface gloss 06

Color perception of 3D objects: Constancy with respect to va...

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3rd symposium on applied perception in graphics and visualization, APGV 2006

作者： Xiao, Bei Brainard, David H. University of Pennsylvania

ISBN: (纸本)1595934294

What determines the color appearance of real objects viewed under natural conditions'? The light reflected from different locations on a single object can vary enormously. This variation is enhanced when the material properties of the object are changed from matte to glossy. Yet humans have no trouble assigning a color name to most things. We studied how people perceive the color of spheres in complex scenes. Observers viewed graphics simulations of a three-dimensional scene containing two spheres, test and match. The observer's task was to adjust the match sphere until its color appearance was the same as that of the test sphere. The match sphere was always matte, and observers varied its color by changing the simulated spectral reflectance function. The surface gloss of the test spheres was varied across conditions. The data show that for fixed test sphere body reflectance, color appearance depends on surface gloss. This effect is small, however, compared to the variation that would be expected if observers simply matched the average of the light reflected from the test. Copyright © 2006 by the Association for Computing Machinery, Inc.

关键词： Three dimensional computer graphics

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visualization with smooth oriented textures and flows: Insights from perception 06

Visualization with smooth oriented textures and flows: Insig...

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3rd symposium on applied perception in graphics and visualization, APGV 2006

作者： Ben-Shahar, Ohad Department of Computer Science Ben-Gurion University Israel

ISBN: (纸本)1595934294

Oriented textures and smooth flows are common texture patterns in visualization, non-photorealistic rendering, and graphical depictions of 3D objects. While these patterns have been partially studied in terms of their contribution to the inference of 3D shape, early visual aspects of their perception, and in particular, their segregation and perceptual organization into coherent parts, have been largely ignored. Here we explore the perception of such smoothly varying oriented textures and flow patterns in order to provide several insights and formal constraints to their constructive use in graphics and visualization. First, we challenge the view that salient perceptual singularities between perceptually coherent regions in orientation-defined textures (ODTs) are tightly dependent upon outstanding contrasts (a.k.a. gradients, or discontinuities) in their local orientation. Unfortunately, this widely accepted view has emerged from two decades of psychophysical research into orientation-based texture segregation (OBTS) which focused mostly on piecewise constant ODTs. A more general inquiry, however, into ODTs of smoothly varying orientation, reveals new perceptual phenomena. In particular, as we show here, completely smooth oriented patterns exhibit striking perceptual singularities that often are mistaken for discontinuities, and are neither predictable from orientation contrasts nor are they detectable by popular segmentation algorithms (Fig. 1). In contrast to existing perceptual models, we then show that our previous (differential) geometric analysis of oriented patterns [BenShahar and Zucker 2003] can be extended into a new theory that fully predicts the observed perceptual singularities using a novel computational "perceptual singularities measure" (PSM): PSM(x,y)= ∏κT2+κN2>τ(Ridges[κN(x,y) 2/κT(x,y)2 + κN(x,y) 2]) (1) where κT(x,y) and κN(x,y) are the tangential and normal curvatures of the pattern, Ridges() returns the set of ridge points of its argument functi

关键词： visualization

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Rendering complex scenes for psychophysics using RADIANCE: How accurate can you get?

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2006年第4期23卷 759-768页

作者： Ruppertsberg, AI Bloj, M Univ Bradford Dept Optometry Bradford BD7 1DP W Yorkshire England

Rendering packages are used by visual psychophysicists to produce complex stimuli for their experiments, tacitly assuming that the simulation results accurately reflect the light-surface interactions of a real scene. RADIANCE is a physically based, freely available, and commonly used rendering software. We validated the calculation accuracy of this package by comparing simulation results with measurements from real scenes. RADIANCE recovers color gradients well but the results are shifted in color space. Currently, there is no better simulation alternative for achieving physical accuracy than by combining a spectral rendering method with RADIANCE. (c) 2006 Optical Society of America.

关键词： BINOCULARLY VIEWED SCENES SURFACE COLOR-perception GLOBAL ILLUMINATION CONSTANCY REPRODUCTION SIMULATIONS VALIDATION SHAPE

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Verification of rendering quality from measured BTFs 06

Verification of rendering quality from measured BTFs

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3rd symposium on applied perception in graphics and visualization, APGV 2006

作者： Meseth, Jan Müller, Gero Klein, Reinhard Röder, Florian Arnold, Michael Institute for Computer Science II Universität Bonn Germany IC:IDO GmbH Stuttgart Germany DaimlerChrysler AG Sindelfingen Germany

ISBN: (纸本)1595934294

One of the most important, still unsolved problems in computer graphics is the generation of predictive imagery, i.e., images that represent perfect renditions of reality. Such perfect images are required in application areas like Virtual Prototyping for making reliable decisions in the costly design development of novel products like cars and airplanes. Recently, measured material properties received significant attention since they enable generation of highly accurate images that appear to be predictive at a first glance. In this work we investigate the degree of realism that can be achieved using measured bidirectional texture functions (BTFs) by comparing photographs and rendered images at two scales. To analyze the realism of rendered images at a coarse scale, we compare the light distribution resulting from standard materials to the one from measured BTFs by automatic procedures. At a fine scale, accurate reproduction of material structures is checked by a psychophysical study. Our results show that measured BTFs lead to much more accurate results than standard materials at both scales. Copyright © 2006 by the Association for Computing Machinery, Inc.

关键词： Computer graphics

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perception of Image Motion during Head Movement 06

Perception of Image Motion during Head Movement

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3rd symposium on applied perception in graphics and visualization, APGV 2006

作者： Li, Li Adelstein, Bernard D. Ellis, Stephen R. Human Systems Integration Division NASA Ames Research Center Moffett Field CA 94035 San Jose State University Foundation San Jose CA 9517 Department of Psychology University of Hong Kong Pokfulam Road Hong Kong Hong Kong

ISBN: (纸本)1595934294

Previous studies have shown that self-motion has an inhibiting effect on concurrent 3D motion perception. To investigate whether self-motion similarly impairs concurrent image motion perception, we examined human perception of head-referenced horizontal image motion during head movement. The displayed stimulus was composed of a checkerboard image in a head mounted display oscillating from side to side at four frequencies (0.25, 0.5, 1 and 2 Hz) with half peak-to-peak amplitudes ranging from 0° to 5.64. Eight observers rated the magnitude of the checkerboard motion while either rotating their head about a vertical axis (yaw), about a horizontal axis (pitch), or holding it still. For all image oscillation frequencies, perceptual sensitivity to image motion amplitude was reduced during both horizontal and vertical head movements (mean reduction: 0.44 and 0.17, respectively). In contrast, perceptual bias was affected only at 2 Hz (mean shift: -9.9% and -12.2% of the full image motion amplitude for horizontal and vertical head movements, respectively). The results indicate that head movement causes gain reductions in motion magnitude estimation at image oscillation frequencies &le1 Hz. At an oscillation frequency of 2 Hz, head movement produces both a gain reduction and a bias shift. Virtual environment developers could take advantage of such effects by relaxing requirements for image stability as well as motion fidelity during head movement. Copyright © 2006 by the Association for Computing Machinery, Inc.

关键词： Sensory perception

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Presence, rather than prior exposure, is the more strongly indicated factor in the accurate perception of egocentric distances in real world co-located immersive virtual environments 06

Presence, rather than prior exposure, is the more strongly i...

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3rd symposium on applied perception in graphics and visualization, APGV 2006

作者： Ries, Brian Interrante, Victoria Anderson, Lee Lindquist, Jason Department of Computer Science University of Minnesota Department of Architecture University of Minnesota

ISBN: (纸本)1595934294

In recent work [4,2], we have discovered that people are able to make surprisingly accurate judgments about egocentric distances in an immersive virtual environment (IVE) in the special case that the IVE represents a high fidelity model of the same physical space that the user is actually occupying, and the user has been able to unambiguously verify this by viewing the real space prior to donning the display upon which the corresponding virtual environment is presented. Through followup experiments in multiple locales, we have verified that the key factor enabling this distance perception accuracy is fact of co-location, rather than any particular characteristics of the physical environment [1]. One possible interpretation of these intriguing results is that observers are better enabled to make accurate judgments of egocentric distance in an IVE when they are when they are cognitively 'immersed' or 'present' in the IVE - i.e. when they readily accept the virtual environment as being 'equivalent' to the real world and are therefore prepared to act in the virtual world in the same way that they act in the real world [3]. However, another interpretation is also possible: it could be that people are able to make accurate judgments of egocentric distances in a virtual environment when they know that it exactly corresponds to a recently viewed real environment because they are able to form a metrically accurate mental model of the spatial structure of the real environment from their brief exposure to it, so that when they are subsequently presented with the virtual environment they simply calibrate their mental model of distances in the IVE to be consistent with their remembered model of the corresponding real environment. In order to disambiguate between the 'presence' hypothesis and the 'spatial memory' hypothesis, we conducted the following study. Using a between-subjects design, we asked observers to make judgments of egocentric distance via blind walking in a real ro

关键词： Sensory perception

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A comparison of immersive HMD, fish tank VR and fish tank with haptics displays for volume visualization 06

A comparison of immersive HMD, fish tank VR and fish tank wi...

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3rd symposium on applied perception in graphics and visualization, APGV 2006

作者： Qi, Wen Taylor Ii, Russell M. Healey, Christopher G. Martens, Jean-Bernard Eindhoven University of Technology UNC Chapel Hill North Carolina State University

ISBN: (纸本)1595934294

Although a wide range of virtual reality (VR) systems are in use, there are few guidelines to help system and application developers select the components most appropriate for the domain problem they are investigating. Using the results of an empirical study, we developed such guidelines for the choice of display environment for four specific, but common, volume visualization problems: identification and judgment of the size, shape, density, and connectivity of objects present in a volume. These tasks are derived from questions being asked by collaborators studying Cystic Fibrosis (CF). We compared user performance in three different stereo VR systems: (1) head-mounted display (HMD);(2) fish tank VR (fish tank);and (3) fish tank VR augmented with a haptic device (haptic). HMD participants were placed "inside" the volume and walked within it to explore its structure. Fish tank and haptic participants saw the entire volume on-screen and rotated it to view it from different perspectives. Response time and accuracy were used to measure performance. Results showed that the fish tank and haptic groups were significantly more accurate at judging the shape, density, and connectivity of objects and completed the tasks significantly faster than the HMD group. Although the fish tank group was itself significantly faster than the haptic group, there were no statistical differences in accuracy between the two. Participants classified the HMD system as an "inside-out" display (looking outwards from inside the volume), and the fish tank and haptic systems as "outside-in" displays (looking inwards from outside the volume). Including haptics added an inside-out capability to the fish tank system through the use of touch. We recommend an outside-in system because it offers both overview and context, two visual properties that are important for the volume visualization tasks we studied. In addition, based on the haptic group's opinion (80% positive) that haptic feedback aided comprehe

关键词： Virtual reality

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Music Icons: Procedural Glyphs for Audio Files

Music Icons: Procedural Glyphs for Audio Files

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Brazilian symposium on Computer graphics and Image Processing (SIBGRAPI)

作者： Philipp Kolhoff Jacqueline Preub Jorn Loviscach Hochschule Bremen University of Applied Sciences Fachbereich Elektrotechnik und Informatik Bremen Germany

Nowadays, a personal music collection may comprise thousands of MP3 files. visualization can help the user to gain an overview and to find similar songs inside so large a set. We describe a method to create icons from audio files in such a way that songs which the user considers similar receive similar icons. This allows visual data mining in standard directory listings of window-based operating systems. The icons consist of bloom-like shapes, whose form and color depend on eight parameters. These parameters are controlled through a neural net, the input of which are audio features that are extracted algorithmically from the MP3 files. To adapt the system to the user's perception and interests, the neural net is initially trained with a small set of songs and icons. User studies done on the system demonstrate a strong perceptual relation between music and icons

关键词： Digital audio players Operating systems Neural networks Data visualization Data mining Feature extraction Two dimensional displays Auditory displays Prototypes Shape

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