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Proceedings of the 1992 Workshop on Volume Visualization

作者： Novins, Kevin Arvo, James Program of Computer Graphics Cornell University Ithaca 14853 NY United States

ISBN: (纸本)0897915275

Traditional methods for evaluating the low-Albedo volume rendering integral do not include bounds on the magnitude of approximation error. In this paper, we examine three techniques for solving this integral with error bounds: Trapezoid rule, Simpson's rule, and a power series method. In each case, the expression for the error bound provides a mechanism for computing the integral to any specified precision. The formulations presented are appropriate for polynomial reconstruction from point samples;however, the approach is considerably mom general. The three techniques we present differ in relative efficiency for computing results to a given precision. The trapezoid rule and Simpson's rule are most efficient for low-to medium-precision solutions. The power series method converges rapidly to a machine precision solution, providing both an efficient means for high-Accuracy volume rendering, and a reference standard by which other approximations may be measured. ©1992 ACM.

关键词： Numerical quadrature Scientific visualization Volume rendering

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Synthetic texturing using digital filters 80

Synthetic texturing using digital filters

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7th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1980

作者： Feibush, Eliot A. Levoy, Marc Cook, Robert L. Program of Computer Graphics Cornell University IthacaNY14853 United States

ISBN: (纸本)0897910214

Aliasing artifacts are eliminated from computer generated images of textured polygons by equivalently filtering both the texture and the edges of the polygons. Different filters can be easily compared because the weighting functions that define the shape of the filters are pre-computed and stored in lookup tables. A polygon subdivision algorithm removes the hidden surfaces so that the polygons are rendered sequentially to minimize accessing the texture definition files. An implementation of the texture rendering procedure is described. � ACM. All rights reserved.

关键词： Anti-aliasing

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Tutorial on color science

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The Visual computer 1986年第5期2卷 278-290页

作者： Meyer, Gary W. Program of Computer Graphics Cornell University Ithaca 14853 NY 120 Rand Hall United States

The principles of tristimulus colorimetry are presented in tutorial fashion. The classic color matching experiments are described with an emphasis on the assumptions that are implicit in these tests and on the units of measure which should be used to record the results. The transformation to alternative sets of primaries is derived and the geometry of the resulting color spaces is illustrated. An annotated bibliography of relevant literature is also provided. © 1986 Springer-Verlag.

关键词： Color science computer graphics Human factors

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Perceptually Based Tone Mapping of High Dynamic Range Image Streams

Perceptually Based Tone Mapping of High Dynamic Range Image ...

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16th Eurographics Symposium on Rendering Techniques, EGSR 2005

作者： Irawan, Piti Ferwerda, James A. Marschner, Stephen R. Department of Computer Science Program of Computer Graphics Cornell University United States

ISBN: (纸本)3905673231

This paper presents a new perceptually based tone mapping operator that represents scene visibility under time-varying, high dynamic range conditions. The operator is based on a new generalized threshold model that extends the conventional threshold-versus-intensity (TVI) function to account for the viewer’s adaptation state, and a new temporal adaptation model that includes fast and slow neural mechanisms as well as photopigment bleaching. These new visual models allow the operator to produce tone-mapped image streams that represent the loss of visibility experienced under changing illumination conditions and in high dynamic range scenes. By varying the psychophysical data that the models use, we simulate the differences in scene visibility experienced by normal and visually impaired observers. © The Eurographics Association 2005.

关键词： Visibility

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ASSESSING THE EFFECT OF SHAPE DISTORTION IN Q9 MEMBRANE ELEMENTS

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computerS & STRUCTURES 1989年第5期33卷 1183-1190页

作者： SALMON, DC ABEL, JF Depart ment of Architecture Cornell University Ithaca NY 14853 U.S.A. School of Civil and Environmental Engineering Program of Computer Graphics Cornell University Ithaca NY 14853 U.S.A.

The Q9 membrane finite element is unable to experience arbitrary change of uniaxial curvature without the occurence of artificial membrane stains. The error which accumulates due to this inability can be significant when a large change of curvature is experienced by this element. This paper investigates the effect of element shape distortion on the accumulation of error in the Q9 membrane element, and presents two methods for evaluating shape distortion effects in problems with large changes of curvature: a series of ‘patch tests’, and single element tests.

关键词： Membranes

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Effects of rendering on shape perception in automobile design 04

Effects of rendering on shape perception in automobile desig...

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Proceedings - 1st Symposium on Applied Perception in graphics and Visualization, APGV 2004

作者： Ferwerda, James A. Westin, Stephen H. Smith, Randall C. Pawlicki, Richard Program of Computer Graphics Cornell University United States General Motors R and D

ISBN: (纸本)1581139144

The goal of this project was to determine if advanced rendering methods such as global illumination allow more accurate discrimination of shape differences than standard rendering methods such as OpenGL. To address these questions, we conducted two psychophysical experiments to measure observers' sensitivity to shape differences between a physical model and rendered images of the model. Two results stand out: The rendering method used has a significant effect on the ability to discriminate shape. In particular, under the conditions tested, global illumination rendering improves sensitivity to shape differences. Further, viewpoint appears to have an effect on the ability to discriminate shape. In most of the cases studied, sensitivity to small shape variations was poorer when the rendering and model viewpoints were different. The results of this work have important implications for our understanding of human shape perception and for the development of rendering tools for computer-aided design.

关键词： Sensory perception

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Perceptual illumination components: A new approach to efficient, high quality global illumination rendering 04

Perceptual illumination components: A new approach to effici...

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ACM SIGGRAPH 2004

作者： Stokes, William A. Ferwerda, James A. Walter, Bruce Greenberg, Donald P. Program of Computer Graphics Cornell University 580 Rhodes Hall Ithaca NY 14853

ISBN: (纸本)9781450378239

In this paper we introduce a new perceptual metric for efficient, high quality, global illumination rendering. The metric is based on a rendering-by-components framework in which the direct, and indirect diffuse, glossy, and specular light transport paths are separately computed and then composited to produce an image. The metric predicts the perceptual importances of the computationally expensive indirect illumination components with respect to image quality. To develop the metric we conducted a series of psychophysical experiments in which we measured and modeled the perceptual importances of the components. An important property of this new metric is that it predicts component importances from inexpensive estimates of the reflectance properties of a scene, and therefore adds negligible overhead to the rendering process. This perceptual metric should enable the development of an important new class of efficient global-illumination rendering systems that can intelligently allocate limited computational resources, to provide high quality images at interactive rates. © 2004 ACM.

关键词： Image analysis

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Design and Simulation of Opera Lighting and Projection Effects 91

Design and Simulation of Opera Lighting and Projection Effec...

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18th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1991

作者： Dorsey, Julie O B. Sillion, Francois X. Greenberg, Donald P. Program of Computer Graphics Cornell University Ithaca New York14853 United States

ISBN: (纸本)0897914368

A major problem challenging opera designers is the inability to coordinate lighting, projection systems, and set designs in the preliminary planning phase. New computer graphics techniques, which provide the set and lighting designer [be opportunity to evaluate, test, and control opera designs prior to the construction of full scale systems are presented, These techniques-light source input. simulation of directional lighting, modeling of scenic projection systems, and full three-dimensional simulation-show the potential for the use of computer graphics in theater design, The light source input component consists of a program for assigning light source attributes with a set of theater lighting icons. This module allows a designer to specify light source characteristics in a way familiar to the discipline and to make preliminary evaluations of the lighting conditions. An extended progressive radiosity method is introduced to simulate the directional lighting characteristics which are specified by the input program. A new projection approach is presented to simulate the optical effects of scenic projectors. In addition, a solution to the distortion problem produced by angular projections is described. The above components are integrated to produce full threedimensional simulations of the global illumination effects in an opera scene. © 1991 ACM.

关键词： Light sources

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Jigsaw image mosaics 02

Jigsaw image mosaics

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ACM Transactions on graphics;Proceedings of ACM SIGGRAPH 2002

作者： Kim, Junhwan Pellacini, Fabio Dept. of Computer Science Cornell University Ithaca NY United States Program of Computer Graphics Cornell University Ithaca NY United States

ISBN: (纸本)9781581135213

This paper introduces a new kind of mosaic, called Jigsaw Image Mosaic (JIM), where image tiles of arbitrary shape are used to compose the final picture. The generation of a Jigsaw Image Mosaic is a solution to the following problem: given an arbitrarily-shaped container image and a set of arbitrarily-shaped image tiles, fill the container as compactly as possible with tiles of similar color to the container taken from the input set while optionally deforming them slightly to achieve a more visually-pleasing effect. We approach the problem by defining a mosaic as the tile configuration that minimizes a mosaicing energy function. We introduce a general energy-based framework for mosaicing problems that extends some of the existing algorithms such as Photomosaics and Simulated Decorative Mosaics. We also present a fast algorithm to solve the mosaicing problem at an acceptable computational cost. We demonstrate the use of our method by applying it to a wide range of container images and tiles.

关键词： Color computer graphics

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Direct illumination with lazy visibility evaluation 99

Direct illumination with lazy visibility evaluation

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26th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1999

作者： Hart, David Dutré, Philip Greenberg, Donald P. Program of Computer Graphics Cornell University 580 Rhodes Hall IthacaNY14850 United States

ISBN: (纸本)0201485605

In this paper we present a technique for computing the direct lighting in a three-dimensional scene containing area light sources. Our method correctly handles partial visibility between luminaires and receivers, and is able to efficiently generate accurate soft shadows in scenes modeled with general bidirectional reflectance distribution functions. In most current algorithms, the form factor between a light source and receiver is computed using a stochastic ray casting approach which evaluates partial visibility. Such an approach often leads to noisy artifacts or aliasing problems. Generating significantly more rays is often the only solution to improving image quality. Our approach first stores visibility information in the image plane, using lazy evaluation of the visibility function. In a second phase, illumination values for each pixel are generated, using analytic or stochastic integration. Soft shadows and other shading effects are generated with high accuracy in less time than with existing shading algorithms. Coherence in specific blocker light source relationships across the image plane is exploited to amortize the cost of analytic form factor calculations. By storing information in the image plane, our method is currently designed for generating a single image, and is thus view-dependent. Copyright ACM 1999.

关键词： Distribution functions

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