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 hav...
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For most first-person video games it is important that players have a high level of feeling presence in the displayed game environment. Virtual reality (VR) technologies have enormous potential to enhance gameplay sin...
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The display units integrated in todays head-mounted displays (HMDs) provide only a limited field of view (FOV) to the virtual world. In order to present an undistorted view to the virtual environment (VE), the perspec...
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Volume raycasting techniques are important for both visual arts and visualization. They allow efficient generation of visual effects and visualization of scientific data obtained by tomography or numerical simulation....
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ISBN:
(纸本)9781450379380
Volume raycasting techniques are important for both visual arts and visualization. They allow efficient generation of visual effects and visualization of scientific data obtained by tomography or numerical simulation. Volume-rendering techniques are also effective for direct rendering of implicit surfaces used for soft-body animation and constructive solid geometry. The focus of this course is on volumetric illumination techniques that approximate physically based light transport in participating media. Such techniques include interactive implementation of soft and hard shadows, ambient occlusion, and simple Monte Carlo-based approaches to global illumination, including translucency and scattering.
In this paper we propose the Arch-Explore user interface, which supports natural exploration of architectural 3D models at different scales in a real walking virtual reality (VR) environment such as head-mounted displ...
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In this paper we propose the Arch-Explore user interface, which supports natural exploration of architectural 3D models at different scales in a real walking virtual reality (VR) environment such as head-mounted display (HMD) or CAVE setups. We discuss in detail how user movements can be transferred to the virtual world to enable walking through virtual indoor environments. To overcome the limited interaction space in small VR laboratory setups, we have implemented redirected walking techniques to support natural exploration of comparably large-scale virtual models. Furthermore, the concept of virtual portals provides a means to cover long distances intuitively within architectural models. We describe the software and hardware setup and discuss benefits of Arch-Explore.
The triangle-perimeter 2-site distance function defines the "distance" P(x, (p, q)) from a point x to two other points p, q as the perimeter of the triangle whose vertices are x, p, q. Accordingly, given a s...
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The triangle-perimeter 2-site distance function defines the "distance" P(x, (p, q)) from a point x to two other points p, q as the perimeter of the triangle whose vertices are x, p, q. Accordingly, given a set S of n points in the plane, the Voronoi diagram of S with respect to P, denoted as V P (S), is the subdivision of the plane into regions, where the region of p, q ¿ S is the locus of all points closer to p, q (according to P) than to any other pair of sites in S. In this paper we prove a theorem about the perimeters of triangles, two of whose vertices are on a given circle. We use this theorem to show that the combinatorial complexity of V P (S) is O(n 2+¿ ) (for any ¿ > 0). Consequently, we show that one can compute V P (S) on O(n 2+¿ ) time and space.
Traveling through virtual environments (VEs) by means of real walking is a challenging task since usually the size of the virtual world exceeds the size of the tracked interaction space. Redirected walking is one conc...
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Redirected walking allows users to walk through large-scale immersive virtual environments (IVEs) while physically remaining in a reasonably small workspace by intentionally injecting scene motion into the IVE. In a c...
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ISBN:
(纸本)9781595939517
Redirected walking allows users to walk through large-scale immersive virtual environments (IVEs) while physically remaining in a reasonably small workspace by intentionally injecting scene motion into the IVE. In a constant stimuli experiment with a twoalternative-forced-choice task we have quantified how much humans can unknowingly be redirected on virtual paths which are different from the paths they actually walk. 18 subjects have been tested in four different experiments: (E1a) discrimination between virtual and physical rotation, (E1b) discrimination between two successive rotations, (E2) discrimination between virtual and physical translation, and discrimination of walking direction (E3a) without and (E3b) with start-up. In experiment E1a subjects performed rotations to which different gains have been applied, and then had to choose whether or not the visually perceived rotation was greater than the physical rotation. In experiment E1b subjects discriminated between two successive rotations where different gains have been applied to the physical rotation. In experiment E2 subjects chose if they thought that the physical walk was longer than the visually perceived scaled travel distance. In experiment E3a subjects walked a straight path in the IVE which was physically bent to the left or to the right, and they estimate the direction of the curvature. In experiment E3a the gain was applied immediately, whereas the gain was applied after a start-up of two meters in experiment E3b. Our results show that users can be turned physically about 68% more or 10% less than the perceived virtual rotation, distances can be up-or down-scaled by 22%, and users can be redirected on an circular arc with a radius greater than 24 meters while they believe they are walking straight. Copyright 2008 ACM.
Volume raycasting techniques are important for both visual arts and. They allow an efficient generation of visual effects and visualization of scientific data obtained by tomography or numerical. Thanks to their flexi...
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Volume raycasting techniques are important for both visual arts and. They allow an efficient generation of visual effects and visualization of scientific data obtained by tomography or numerical. Thanks to their flexibility, experts agree that GPU-based is the state-of-the art technique for interactive volume *** most likely replace existing slice-based techniques in the near. Volume rendering techniques are also effective for the direct rendering implicit surfaces used for soft body animation and constructive *** starts off with an in-depth introduction to the concepts GPU-based ray-casting to provide a common base for the following. The focus of this course is on advanced illumination techniques approximate the physically-based light transport more convincingly. techniques include interactive implementation of soft hard shadows, ambient occlusion and simple Monte-Carlo based approaches global illumination including translucency and scattering. the proposed techniques, users are le to interactively create images from volumetric data whose visual quality goes far traditional approaches. The optical properties in participating are defined using the phase function. Many approximations to the based light transport applied for rendering natural phenomena as clouds or smoke assume a rather homogenous phase function. For rendering volumetric scans on the other hand different phase models are required to account for both surface-like structures fuzzy boundaries in the data. Using volume rendering techniques,who create medical visualization for science magazines may now work on tomographic scans directly, without the necessity to fall back to creating polygonal models of anatomical structures.
Traveling through immersive virtual environments (IVEs) by means of real walking is an important activity to increase naturalness of VR-based interaction. However, the size of the virtual world often exceeds the size ...
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Traveling through immersive virtual environments (IVEs) by means of real walking is an important activity to increase naturalness of VR-based interaction. However, the size of the virtual world often exceeds the size of the tracked space so that a straightforward implementation of omni-directional and unlimited walking is not possible. Redirected walking is one concept to solve this problem of walking in IVEs by inconspicuously guiding the user on a physical path that may differ from the path the user visually perceives. When the user approaches a virtual object she can be redirected to a real proxy object that is registered to the virtual counterpart and provides passive haptic feedback. In such passive haptic environments, any number of virtual objects can be mapped to proxy objects having similar haptic properties, e.g., size, shape and texture. The user can sense a virtual object by touching its real world counterpart. Redirecting a user to a registered proxy object makes it necessary to predict the user's intended position in the IVE. Based on this target position we determine a path through the physical space such that the user is guided to the registered proxy object. We present a taxonomy of possible redirection techniques that enable user guidance such that inconsistencies between visual and proprioceptive stimuli are imperceptible. We describe how a user's target in the virtual world can be predicted reliably and how a corresponding real-world path to the registered proxy object can be derived.
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