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392
Stereo Matching with Transparency and Matting
 IJCV
, 1998
"... This paper formulates and solves a new variant of the stereo correspondence problem: simultaneously recovering the disparities, true colors, and opacities of visible surface elements. This problem arises in newer applications of stereo reconstruction, such as view interpolation and the layering of r ..."
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Cited by 97 (17 self)
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This paper formulates and solves a new variant of the stereo correspondence problem: simultaneously recovering the disparities, true colors, and opacities of visible surface elements. This problem arises in newer applications of stereo reconstruction, such as view interpolation and the layering of real imagery with synthetic graphics for special effects and virtual studio applications. While this problem is intrinsically more difficult than traditional stereo correspondence, where only the disparities are being recovered, it provides a principled way of dealing with commonly occurring problems such as occlusions and the handling of mixed (foreground/background) pixels near depth discontinuities. It also provides a novel means for separating foreground and background objects (matting), without the use of a special blue screen. We formulate the problem as the recovery of colors and opacities in a generalized 3D (x, y, d) disparity space, and solve the problem using a combination of initial evidence aggregation followed by iterative energy minimization.
ImageBased Rendering for NonDiffuse Synthetic Scenes
, 1998
"... . Most current imagebased rendering methods operate under the assumption that all of the visible surfaces in the scene are opaque ideal diffuse (Lambertian) reflectors. This paper is concerned with imagebased rendering of nondiffuse synthetic scenes. We introduce a new family of imagebased scene ..."
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Cited by 94 (1 self)
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. Most current imagebased rendering methods operate under the assumption that all of the visible surfaces in the scene are opaque ideal diffuse (Lambertian) reflectors. This paper is concerned with imagebased rendering of nondiffuse synthetic scenes. We introduce a new family of imagebased scene representations and describe corresponding imagebased rendering algorithms that are capable of handling general synthetic scenes containing not only diffuse reflectors, but also specular and glossy objects. Our imagebased representation is based on layered depth images. It represents simultaneously and separately both viewindependent scene information and viewdependent appearance information. The viewdependent information may be either extracted directly from our datastructures, or evaluated procedurally using an imagebased analogue of ray tracing. We describe imagebased rendering algorithms that recombine the two components together in a manner that produces a good approximation to...
Frequency Domain Volume Rendering
, 1993
"... The Fourier projectionslice theorem allows projections of volume data to be generated in O(n 2 log n) time for a volume of size n 3 . The method operates by extracting and inverse Fourier transforming 2D slices from a 3D frequency domain representation of the volume. Unfortunately, these projec ..."
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Cited by 93 (0 self)
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The Fourier projectionslice theorem allows projections of volume data to be generated in O(n 2 log n) time for a volume of size n 3 . The method operates by extracting and inverse Fourier transforming 2D slices from a 3D frequency domain representation of the volume. Unfortunately, these projections do not exhibit the occlusion that is characteristic of conventional volume renderings. We present a new frequency domain volume rendering algorithm that replaces much of the missing depth and shape cues by performing shading calculations in the frequency domain during slice extraction. In particular, we demonstrate frequency domain methods for computing linear or nonlinear depth cueing and directional diffuse reflection. The resulting images can be generated an order of magnitude faster than volume renderings and may be more useful for many applications. CR Categories: I.3.7 [Computer Graphics]: Threedimensional Graphics and Realism.; I.3.3 [Computer Graphics ]: Picture/Image Generati...
Realtime Exploration of Regular Volume Data by Adaptive Reconstruction of IsoSurfaces
 The Visual Computer
, 1999
"... Recent advances in the technology of 3D sensors and in the performance of numerical simulations result in the generation of volume data at ever growing size. In order to allow realtime exploration of even the highest resolution data sets, adaptive techniques benefiting from the hierarchical nature ..."
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Cited by 93 (3 self)
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Recent advances in the technology of 3D sensors and in the performance of numerical simulations result in the generation of volume data at ever growing size. In order to allow realtime exploration of even the highest resolution data sets, adaptive techniques benefiting from the hierarchical nature of multiresolution representations have gained special attention. In this paper we propose an adaptive approach to the fast reconstruction of isosurfaces from regular volume data at arbitrary levels of detail. The algorithm has been designed to enable realtime navigation through complex structures while providing useradjustable resolution levels. Since adaptive onthefly reconstruction and rendering is performed from a hierarchical octree representation of the volume data, the method does not depend on preprocessing with respect to a specific isovalue thus allowing the user to interactively browse through the pencil of isosurfaces. Special attention is paid to the fixing of cracks in...
Volume Rendering on Scalable SharedMemory MIMD Architectures
, 1992
"... Volume rendering is a useful visualization technique for understanding the large amounts of data generated in a variety of scientific disciplines. Routine use of this technique is currently limited by its computational expense. We have designed a parallel volume rendering algorithm for MIMD architec ..."
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Cited by 75 (0 self)
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Volume rendering is a useful visualization technique for understanding the large amounts of data generated in a variety of scientific disciplines. Routine use of this technique is currently limited by its computational expense. We have designed a parallel volume rendering algorithm for MIMD architectures based on ray tracing and a novel task queue image partitioning technique. The combination of ray tracing and MIMD architectures allows us to employ algorithmic optimizations such as hierarchical opacity enumeration, early ray termination, and adaptive image sampling. The use of task queue image partitioning makes these optimizations efficient in a parallel framework. We have implemented our algorithm on the Stanford DASH Multiprocessor, a scalable sharedmemory MIMD machine. Its single addressspace and coherent caches provide programming ease and good performance for our algorithm. With only a few days of programming effort, we have obtained nearly linear speedups and near realtime frame update rates on a 48 processor machine. Since DASH is constructed from Silicon Graphics multiprocessors, our code runs on any Silicon Graphics workstation without modification.
A Multiresolution Framework for Volume Rendering
 SYMPOSIUM ON VOLUME VISUALIZATION
, 1994
"... In this paper we present a general framework for the approximation of the volume rendering integral using multiresolution spaces. Instead of solving the integral over the original volume data set we first project it into a wavelet basis. The final integration process is then performed on the resulti ..."
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Cited by 74 (6 self)
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In this paper we present a general framework for the approximation of the volume rendering integral using multiresolution spaces. Instead of solving the integral over the original volume data set we first project it into a wavelet basis. The final integration process is then performed on the resulting coefficients directly. Depending on the used basis functions a large number of coefficients can be neglected while still achieving accurate results. This leads to a drastic reduction in the amount of memory used during the rendering process. Furthermore, this sparse representation can be integrated into the rendering process, which is reflected in the overall rendering times.
Accelerating Volume Animation by SpaceLeaping
, 1993
"... f i In this paper we present a method for speeding the process of volume rendering a sequence o mages. Speedup is based on exploiting coherency between consecutive images to shorten the n path rays take through the volume. This is achieved by providing each ray with information eeded to leap over th ..."
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Cited by 74 (9 self)
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f i In this paper we present a method for speeding the process of volume rendering a sequence o mages. Speedup is based on exploiting coherency between consecutive images to shorten the n path rays take through the volume. This is achieved by providing each ray with information eeded to leap over the empty space and commence volume traversal at the vicinity of mean  b ingful data. The algorithm starts by projecting the volume into a Cbuffer (Coordinates uffer) which stores, at each pixel location, the objectspace coordinates of the first nonempty s t voxel visible from that pixel. For each change in the viewing parameters, the Cbuffer i ransformed accordingly. In the case of rotation the transformed Cbuffer goes through a pro  b cess of eliminating coordinates that possibly became hidden. The remaining values in the C uffer serve as an estimate of the point where the new rays should start their volume traverc sal. This spaceleaping method can be combined with existing accele...
Volume Rendering by Adaptive Refinement
, 1989
"... Volume rendering is a technique for visualizing sampled scalar functions of three spatial dimensions by computing 2D projections of a colored semitransparent gel. This paper presents a volume rendering algorithm in which image quality is adaptively refined over time. An initial image is generated b ..."
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Cited by 64 (5 self)
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Volume rendering is a technique for visualizing sampled scalar functions of three spatial dimensions by computing 2D projections of a colored semitransparent gel. This paper presents a volume rendering algorithm in which image quality is adaptively refined over time. An initial image is generated by casting a small number of rays into the data, less than one ray per pixel, and interpolating between the resulting colors. Subsequent images are generated by alternately casting more rays and interpolating. The usefulness of these rays is maximized by distributing them according to measures of local image complexity. Examples from two applications are given: molecular graphics and medical imaging. Key words: Volume rendering, voxel, adaptive refinement, adaptive sampling, ray tracing. 1. Introduction In this paper, we address the problem of visualizing sampled scalar functions of three spatial dimensions, henceforth referred to as volume data. We focus on a relatively new visualization tec...
TemplateBased Volume Viewing
, 1992
"... We present an efficient threephase algorithm for volume viewing that is based on exploit  t ing coherency between rays in parallel projection. The algorithm starts by building a ray emplate and determining a special plane for projection  the baseplane. Parallel rays are cast t into the volume ..."
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Cited by 64 (17 self)
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We present an efficient threephase algorithm for volume viewing that is based on exploit  t ing coherency between rays in parallel projection. The algorithm starts by building a ray emplate and determining a special plane for projection  the baseplane. Parallel rays are cast t into the volume from within the projected region of the volume on the baseplane, by repeating he sequence of steps specified in the raytemplate. We carefully choose the type of line to be s employed and the way the template is being placed on the baseplane in order to assure uniform ampling of the volume by the discrete rays. We conclude by describing an optimized software K implementation of our algorithm and reporting its performance. eywords: volume rendering, ray casting, template, parallel projection 1. Introduction Volume visualization is the process of converting complex volume data to a format that is p amenable to human understanding while maintaining the integrity and accuracy of the data. Th...
Direct Volume Rendering via 3D Textures
, 1994
"... The advent of very fast texture mapping hardware in modern graphics workstations has warranted research into rendering techniques that use texture mapping to full advantage. We have developed a new and easy to implement method for direct volume rendering that produces highquality images at speeds a ..."
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Cited by 63 (2 self)
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The advent of very fast texture mapping hardware in modern graphics workstations has warranted research into rendering techniques that use texture mapping to full advantage. We have developed a new and easy to implement method for direct volume rendering that produces highquality images at speeds approaching two orders of magnitude faster than existing techniques, on workstations with hardware support for threedimensional texture maps. A rectilinear data set is converted into a threedimensional texture map containing color and opacity information. In the rendering phase, the texture map is then applied to a stack of parallel planes, which effectively cut the texture into many slices. The slices are composited to form an image of the original data set. This paper describes the theory and implementation of this technique. Keywords: Computer Graphics, Scientific Visualization, 3D Texture Mapping, Direct Volume Rendering. 1 Overview Rendering speed has always been a major problem in ...