Results 1  10
of
334
Polygonization of Implicit Surfaces
, 1988
"... This paper discusses a numerical technique that approximates an implicit surface with a polygonal representation. The implicit function is adaptively sampled as it is surrounded by a spatial partitioning. The partitioning is represented by an octree, which may either converge to the surface or track ..."
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Cited by 432 (5 self)
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This paper discusses a numerical technique that approximates an implicit surface with a polygonal representation. The implicit function is adaptively sampled as it is surrounded by a spatial partitioning. The partitioning is represented by an octree, which may either converge to the surface or track it. A piecewise polygonal representation is derived from the octree.
A rapid hierarchical radiosity algorithm
 Computer Graphics
, 1991
"... This paper presents a rapid hierarchical radiosity algorithm for illuminating scenes containing lar e polygonal patches. The afgorithm constructs a hierarchic“J representation of the form factor matrix by adaptively subdividing patches into su bpatches according to a usersupplied error bound. The a ..."
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Cited by 412 (11 self)
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This paper presents a rapid hierarchical radiosity algorithm for illuminating scenes containing lar e polygonal patches. The afgorithm constructs a hierarchic“J representation of the form factor matrix by adaptively subdividing patches into su bpatches according to a usersupplied error bound. The algorithm guarantees that all form factors are calculated to the same precision, removing many common image artifacts due to inaccurate form factors. More importantly, the al orithm decomposes the form factor matrix into at most O? n) blocks (where n is the number of elements). Previous radiosity algorithms represented the elementtoelement transport interactions with n2 form factors. Visibility algorithms are given that work well with this approach. Standard techniques for shooting and gathering can be used with the hierarchical representation to solve for equilibrium radiosities, but we also discuss using a brightnessweighted error criteria, in conjunction with multigrldding, to even more rapidly progressively refine the image.
Efficient ray tracing of volume data
 ACM Transactions on Graphics
, 1990
"... Volume rendering is a technique for visualizing sampled scalar or vector fields of three spatial dimensions without fitting geometric primitives to the data. A subset of these techniques generates images by computing 2D projections of a colored semitransparent volume, where the color and opacity at ..."
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Cited by 390 (4 self)
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Volume rendering is a technique for visualizing sampled scalar or vector fields of three spatial dimensions without fitting geometric primitives to the data. A subset of these techniques generates images by computing 2D projections of a colored semitransparent volume, where the color and opacity at each point are derived from the data using local operators. Since all voxels participate in the generation of each image, rendering time grows linearly with the size of the dataset. This paper presents a fronttoback imageorder volumerendering algorithm and discusses two techniques for improving its performance. The first technique employs a pyramid of binary volumes to encode spatial coherence present in the data, and the second technique uses an opacity threshold to adaptively terminate ray tracing. Although the actual time saved depends on the data, speedups of an order of magnitude have been observed for datasets of useful size and complexity. Examples from two applications are given: medical imaging and molecular graphics.
Generating antialiased images at low sampling densities
 In SIGGRAPH ’87: Proceedings of the 14th annual conference on Computer graphics and interactive techniques, ACM
, 1987
"... Ray tracing produces point samples of an image from a 3D model. Constructing an antialiased digital picture from point samples is difficult without resorting to extremely high sampling densities. This paper describes a program that focuses on that problem. While it is impossible to totally eliminat ..."
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Cited by 187 (7 self)
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Ray tracing produces point samples of an image from a 3D model. Constructing an antialiased digital picture from point samples is difficult without resorting to extremely high sampling densities. This paper describes a program that focuses on that problem. While it is impossible to totally eliminate aliasing, it has been shown that nonuniform sampling yields aliasing that is less conspicuous to the observer. An algorithm is presented for fast generation of nonuniform sampling patterns that are optimal in some sense. Some regions of an image may require extra sampling to avoid strong aliasing. Deciding where to do extra sampling can be guided by knowledge of how the eye perceives noise as a function of contrast and color. Finally, to generate the digital picture, the image must be reconstructed from the samples and resampled at the display pixel rate. The nonuniformity of the samples complicates this process, and a new nonuniform reconstruction filter is presented which solves this problem efficiently. This paper was presented in SIGGRAPH 87.
The Accumulation Buffer: Hardware Support for HighQuality Rendering
, 1990
"... This paper describes a system architecture that supports realtime generation of complex images, efficient generation of extremely highquality images, and a smooth tradeoff between the two. Based on the paradigm of integration, the architecture extends a stateoftheart rendering system with an ad ..."
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Cited by 182 (3 self)
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This paper describes a system architecture that supports realtime generation of complex images, efficient generation of extremely highquality images, and a smooth tradeoff between the two. Based on the paradigm of integration, the architecture extends a stateoftheart rendering system with an additional highprecision image buffer. This additional buffer, called the Accumulation Buffer, is used to integrate images that are rendered into the framebuffer. While originally conceived as a solution to the problem of aliasing, the Accumulation Buffer provides a general solution to the problems of motion blur and depthoffield as well. Because the architecture is a direct extension of current workstation rendering technology, we begin by discussing the performance and quality characteristics of that technology. The problem of spatial aliasing is then discussed, and the Accumulation Buffer is shown to be a desirable solution. Finally the generality of the Accumulation Buffer is explored, concentrating on its application to the problems of motion blur, depthoffield, and soft shadows.
A survey of shadow algorithms
 IEEE Computer Graphics and Applications
, 1990
"... Essential to realistic and visually appealing images, shadows are difficult ta compute in most display environments. This survey characterizes the various types of shadows. It also describes most existing shadow algorithms and discusses their complexities, advantages, and shommings. We examine herd ..."
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Cited by 150 (3 self)
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Essential to realistic and visually appealing images, shadows are difficult ta compute in most display environments. This survey characterizes the various types of shadows. It also describes most existing shadow algorithms and discusses their complexities, advantages, and shommings. We examine herd shadows, soft shadbws, shadows of transparent objects, and shadows for complex modeling primitives. For each type, we examine shadow algorithms within various rendswing techniques. This survey attempts to provide readem with enough background and insight on the various rmthods to dow them to choose the algorithm best wpuited to their W. We also hope that our analysis will h&p identify the a m that need more research and point bo possible sotutkms. A shadowa region of relative darkness within an not necessarily attenuate the light it occludes. In fact, illuminated regionoccurs when an object totally or it can concentrate light. However, as is traditional in partially occludes the light. A transparent object does image synthesis, lve will consider a region to be in
A language for shading and lighting calculations
 Computer Graphics (SIGGRAPH ’90 Proceedings
, 1990
"... A shading language provides a means to extend the shading and lighting formulae used by a rendering system. This paper discusses the design of a new shading language based on previous work of Cook and Perlin. This language has various types of shaders for light sources and surface reflectances, poin ..."
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Cited by 130 (8 self)
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A shading language provides a means to extend the shading and lighting formulae used by a rendering system. This paper discusses the design of a new shading language based on previous work of Cook and Perlin. This language has various types of shaders for light sources and surface reflectances, point and color data types, control flow constructs that support the casting of outgoing and the integration of incident light, a clearly specified interface to the rendering system using global state variables, and a host of useful builtin functions. The design issues and their impact on the implementation are also discussed. CR Categories: 1.3.3 [Computer Graphics] Picture/Image Generation Display algorithms; 1.3.5 [Computer Graphics]
A Ray Tracing Algorithm for Progressive Radiosity, Computer Graphics 23(3
, 1989
"... A new method for computing formfactors within a progressive radiosity approach is presented. Previously, the progressive radiosity approach has depended on the use of the hemicube algorithm to determine formfactors. However, sampling problems inherent in the hemicube algorithm limit its useful ..."
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Cited by 125 (0 self)
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A new method for computing formfactors within a progressive radiosity approach is presented. Previously, the progressive radiosity approach has depended on the use of the hemicube algorithm to determine formfactors. However, sampling problems inherent in the hemicube algorithm limit its usefulness for complex images. A more robust approach is described in which ray tracing is used to perform the numerical integration of the formfactor equation. The approach is tailored to provide good, approximate results for a low number of rays, while still providing a smooth continuum of increasing accuracy for higher numbers of rays. Quantitative comparisons between analytically derived formfactors and ray traced formfactors are presented.
Reconstruction filters in computer graphics
 In Proc. of SIGGRAPH ’88
, 1988
"... Problems of signal processing arise in image synthesis because of transformations between continuous and discrete representations of 2D images. Aliasing introduced by sampling has received much attention in graphics, but reconstruction of samples into a continuous representation can also cause alias ..."
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Cited by 104 (2 self)
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Problems of signal processing arise in image synthesis because of transformations between continuous and discrete representations of 2D images. Aliasing introduced by sampling has received much attention in graphics, but reconstruction of samples into a continuous representation can also cause aliasing as well as other defects in image quality. The problem of designing a filter for use on images is discussed, and a new family of piecewise cubic filters are investigated as a practical demonstration. Tw o interesting cubic filters are found, one having good antialiasing properties and the other having good imagequality properties. It is also shown that reconstruction using derivative as well as amplitude values can greatly reduce aliasing. This paper has been accepted for presentation in SIGGRAPH 88.
Fast hierarchical importance sampling with blue noise properties
 ACM TRANSACTIONS ON GRAPHICS
, 2004
"... This paper presents a novel method for efficiently generating a good sampling pattern given an importance density over a 2D domain. A Penrose tiling is hierarchically subdivided creating a sufficiently large number of sample points. These points are numbered using the Fibonacci number system, and th ..."
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Cited by 104 (8 self)
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This paper presents a novel method for efficiently generating a good sampling pattern given an importance density over a 2D domain. A Penrose tiling is hierarchically subdivided creating a sufficiently large number of sample points. These points are numbered using the Fibonacci number system, and these numbers are used to threshold the samples against the local value of the importance density. Precomputed correction vectors, obtained using relaxation, are used to improve the spectral characteristics of the sampling pattern. The technique is deterministic and very fast; the sampling time grows linearly with the required number of samples. We illustrate our technique with importancebased environment mapping, but the technique is versatile enough to be used in a large variety of computer graphics applications, such as light transport calculations, digital halftoning, geometry processing, and various rendering techniques.