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Proceedings of the 2005 Symposium on Interactive 3D Graphics, SI3D 2005, April 3-6, 2005, Washington, DC, USA; 01/2005
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ABSTRACT: Projector-based Three Dimensional Graphics (Under the direction of Henry Fuchs and Gregory Welch) Light projectors can be arranged into electronic displays that offer large, bright, and high resolution images. However, despite their unique characteristics, projectors have been treated like any other two-dimensional display devices, e.g. CRT monitors or LCD panels, to create flat and usually rectangular images. Even the growth of three dimensional computer graphics has followed this limitation.
04/2004;
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ABSTRACT: We present the "Geometry Video," a new data structure to encode animated meshes. Being able to encode animated meshes in a generic source-independent format allows people to share experiences. Changing the viewpoint allows more interaction than the fixed view supported by 2D video. Geometry videos are based on the "Geometry Image" mesh representation introduced by Gu et al.
06/2003;
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ABSTRACT: We present the design and implementation of a real-time, distributed light field camera. Our system allows multiple viewers to navigate virtual cameras in a dynamically changing light field that is captured in real-time. Our light field camera consists of 64 commodity video cameras that are connected to off-the-shelf computers. We employ a distributed rendering algorithm that allows us to overcome the data bandwidth problems inherent in dynamic light fields. Our algorithm works by selectively transmitting only those portions of the video streams that contribute to the desired virtual views. This technique not only reduces the total bandwidth, but it also allows us to scale the number of cameras in our system without increasing network bandwidth. We demonstrate our system with a number of examples.
03/2003;
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ACM Trans. Graph. 01/2003; 22:759-769.
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ABSTRACT: In this paper we present an efficient algorithm for sampling visual hulls. Our algorithm computes exact points and normals on the surface of visual hull instead of a more traditional volumetric representation. The main feature that distinguishes our algorithm from previous ones is that it allows for sampling along arbitrary viewing rays with no loss of efficiency. Using this property, we adaptively sample visual hulls to minimize the number of samples needed to attain a given fidelity. In our experiments, the number of samples can typically be reduced by an order of magnitude, resulting in a corresponding performance increase over previous algorithms.
08/2002;
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ABSTRACT: In traditional stereoscopic displays, the virtual three-dimensional object does not appear to be fixed in space as the viewer's head moves. This apparent motion results from the fact that a correct stereo image can only be formed for a particular viewpoint and interpupillary distance. At other viewpoints, our brain interprets the stereo image as a slightly skewed and rotated version of the original. When moving the head, this skewing of the image is perceived as apparent motion of the object.
07/2002;
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ABSTRACT: We consider the problem of video stabilization: removing unwanted image perturbations due to unstable camera motions. We approach this problem from an image-based rendering (IBR) standpoint. Given an unstabilized video sequence, the task is to synthesize a new sequence as seen from a stabilized camera trajectory. This task is relatively straightforward if one has a Euclidean reconstruction of the unstabilized camera trajectory and a suitable IBR algorithm. However, it is often not feasible to obtain a Euclidean reconstruction from an arbitrary video sequence. In light of this problem, we describe IBR techniques for non-metric reconstructions, which are often much easier to obtain since they do not require camera calibration. These rendering techniques are well suited to the video stabilization problem. The key idea behind our techniques is that all measurements are specified in the image space, rather than in the non-metric space.
07/2002;
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ABSTRACT: A new approach to telepresence is presented in which amultitude of stationary cameras are used to acquire both photometric and depth information. A virtual environment is constructed by displaying the acquired data from the remote site in accordance with the head position and orientation of a local participant. Shown are preliminary results of a depth image of a human subject calculated from 11 closely spaced video camera positions. A user wearing a head-mounted display walks around this 3D data that has been inserted into a 3D model of a simple room. Future systems based on this approachmay exhibit more natural and intuitiveinteraction among participants than current2D teleconferencing systems.
07/2002;
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ABSTRACT: This paper introduces a new image-based approach to capturing and modeling highly specular, transparent, or translucent objects. We have built a system for automatically acquiring high quality graphical models of objects that are extremely difficult to scan with traditional 3D scanners. The system consists of turntables, a set of cameras and lights, and monitors to project colored backdrops. We use multi-background matting techniques to acquire alpha and environment mattes of the object from multiple viewpoints. Using the alpha mattes we reconstruct an approximate 3D shape of the object. We use the environment mattes to compute a high-resolution surface reflectance field. We also acquire a low-resolution surface reflectance field using the overhead array of lights.
07/2002;
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ABSTRACT: We present the design and implementation of a real-time, distributed light field camera. Our system allows multiple viewers to navigate virtual cameras in a dynamically changing light field that is captured in real-time. Our light field camera consists of 64 commodity video cameras that are connected to off-the-shelf computers. We employ a distributed rendering algorithm that allows us to overcome the data bandwidth problems inherent in dynamic light fields. Our algorithm works by selectively transmitting only those portions of the video streams that contribute to the desired virtual views. This technique not only reduces the total bandwidth, but it also allows us to scale the number of cameras in our system without increasing network bandwidth. We demonstrate our system with a number of examples.
07/2002;
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[show abstract]
[hide abstract]
ABSTRACT: This paper introduces a new image-based approach to capturing and modeling highly specular, transparent, or translucent objects. We have built a system for automatically acquiring high quality graphical models of objects that are extremely difficult to scan with traditional 3D scanners. The system consists of turntables, a set of cameras and lights, and monitors to project colored backdrops. We use multi-background matting techniques to acquire alpha and environment mattes of the object from multiple viewpoints. Using the alpha mattes we reconstruct an approximate 3D shape of the object. We use the environment mattes to compute a high-resolution surface reflectance field. We also acquire a low-resolution surface reflectance field using the overhead array of lights.
07/2002;
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ABSTRACT: We have built a system for acquiring and displaying high quality graphical models of objects that are impossible to scan with traditional scanners. Our system can acquire highly specular and fuzzy materials, such as fur and feathers. The hardware set-up consists of a turntable, two plasma displays, an array of cameras, and a rotating array of directional lights. We use multi-background matting techniques to acquire alpha mattes of the object from multiple viewpoints. The alpha mattes are used to construct an opacity hull.The opacity hull is a new shape representation, defined as the visual hull of the object with view-dependent opacity. It enables visualization of complex object silhouettes and seamless blending of objects into new environments. Our system also supports relighting of objects with arbitrary appearance using surface reflectance fields, a purely image-based appearance representation. Our system is the first to acquire and render surface reflectance fields under varying illumination from arbitrary viewpoints. We have built three generations of digitizers with increasing sophistication. In this paper, we present our results from digitizing hundreds of models.
07/2002;
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ABSTRACT: Determining shape from stereo has often been posed as a global minimization problem. Once formulated, the minimization problems are then solved with a variety of algorithmic approaches. These approaches include techniques such as dynamic programming min-cut and alpha-expansion. In this paper we show how an algorithmic technique that constructs a discrete spatial minimal cost surface can be brought to bear on stereo global minimization problems. This problem can then be reduced to a single min-cut problem. We use this approach to solve a new global minimization problem that naturally arises when solving for three-camera (trinocular) stereo. Our formulation treats the three cameras symmetrically, while imposing a natural occlusion cost and uniqueness constraint.
03/2002;
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ABSTRACT: In this paper we describe an efficient algorithm for computing the visual hull of an object. This problem is equivalent to computing the intersection of generalized cones. The nave visual hull computation algorithm requires intersecting 3D polyhedra. We exploit the special structure of generalized cone polyhedra and show how to reduce this computation to a set of intersections in 2D. Moreover, we describe how the 2D intersections can be carried out efficiently.
03/2002;
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ABSTRACT: This research further develops the light field and lumigraph imagebased rendering methods and extends their utility. We present alternate parameterizations that permit 1) interactive rendering of moderately sampled light fields of scenes with significant, unknown depth variation and 2) low-cost, passive autostereoscopic viewing. Using a dynamic reparameterization, these techniques can be used to interactively render photographic effects such as variable focus and depth-of-field within a light field. The dynamic parameterization is independent of scene geometry and does not require actual or approximate geometry of the scene. We explore the frequency domain and ray-space aspects of dynamic reparameterization, and present an interactive rendering technique that takes advantage of today's commodity rendering hardware.
01/2002;
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10th Pacific Conference on Computer Graphics and Applications (PG 2002), 9-11 October 2002, Beijing, China; 01/2002
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Computer Vision - ECCV 2002, 7th European Conference on Computer Vision, Copenhagen, Denmark, May 28-31, 2002, Proceedings, Part III; 01/2002
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Proceedings of the 13th Eurographics Workshop on Rendering Techniques, Pisa, Italy, June 26-28, 2002; 01/2002
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[show abstract]
[hide abstract]
ABSTRACT: Determining shape from stereo has often been posed as a global minimization problem. Once formulated, the minimization problems
are then solved with a variety of algorithmic approaches. These approaches include techniques such as dynamic programming
min-cut and alpha-expansion. In this paper we show how an algorithmic technique that constructs a discrete spatial minimal
cost surface can be brought to bear on stereo global minimization problems. This problem can then be reduced to a single min-cut
problem. We use this approach to solve a new global minimization problem that naturally arises when solving for three-camera
(trinocular) stereo. Our formulation treats the three cameras symmetrically, while imposing a natural occlusion cost and uniqueness
constraint.
12/2001: pages 1-14;
