检索结果-内蒙古大学图书馆

16th Eurographics Symposium on Rendering Techniques, EGSR 2005

作者： Li, Hongsong Pellacini, Fabio Torrance, Kenneth Program of Computer Graphics Rhodes Hall Cornell University IthacaNY14853 United States

ISBN: (纸本)3905673231

Subsurface scattering is a fundamental aspect of surface appearance responsible for the characteristic look of many materials. Monte Carlo path tracing techniques can be employed with high accuracy to simulate the scattering of light inside a translucent object, albeit at the cost of long computation times. In a seminal work, Jensen et al. [JMLH01] presented a more efficient technique to simulate subsurface scattering that, while producing accurate results for translucent, optically-thick, materials, exhibits artifacts for semi-transparent, optically-thin, ones, especially in regions of high-curvature. This paper presents a hybrid Monte Carlo technique capable of simulating a wide range of materials exhibiting subsurface scattering, from translucent to semi-transparent ones, with an accuracy comparable to Monte Carlo techniques but at a much lower computational cost. Our approach utilizes a Monte Carlo path tracing approach for the first several scattering events, in order to estimate the directional-diffuse component of subsurface scattering, and switches to a dipole diffusion approximation only when the path penetrates deeply enough into the surface. By combining the accuracy of Monte Carlo integration with the efficiency of the dipole diffusion approximation, our hybrid method produces results as accurate as full Monte Carlo simulations at a speed comparable to the Jensen et al. approximation, thus extending its usefulness to a much wider range of materials. © The Eurographics Association 2005.

关键词： Monte Carlo methods

来源：评论

学校读者我要写书评

暂无评论

Feature-Based Textures

Feature-Based Textures

引用

15th Eurographics Workshop on Rendering Techniques, EGSR 2004

作者： Ramanarayanan, G. Bala, K. Walter, B. Department of Computer Science Cornell University IthacaNY United States Program of Computer Graphics Cornell University IthacaNY United States

ISBN: (纸本)3905673126

This paper introduces feature-based textures, a new image representation that combines features and samples for high-quality texture mapping. Features identify boundaries within an image where samples change discontinuously. They can be extracted from vector graphics representations, or explicitly added to raster images to improve sharpness. Texture lookups are then interpolated from samples while respecting these boundaries. We present results from a software implementation of this technique demonstrating quality, efficiency and low memory overhead. © The Eurographics Association 2004.

关键词： Image enhancement

来源：评论

学校读者我要写书评

暂无评论

The irradiance Jacobian for partially occluded polyhedral sources 94

The irradiance Jacobian for partially occluded polyhedral so...

引用

21st Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1994

作者： Arvo, James Program of Computer Graphics Cornell University 580 Engineering and Theory Center Building IthacaNY14853 United States

ISBN: (纸本)0897916670

The irradiance at a point on a surface due to a polyhedral source of uniform brightness is given by a well-known analytic formula. In this paper we derive the corresponding analytic expression for the irradiance Jacobian, the derivative of the vector representation of irradiance. Although the result is elementary for unoccluded sources, within penumbrae the irradiance Jacobianmust incorporate more information about blockers than either the irradiance or vector irradiance. The expression presented here holds for any number of polyhedral blockers and requires only a minor extension of standard polygon clipping to evaluate. To illustrate its use, three related applications are briefly described: direct computation of isolux contours, finding local irradiance extrema, and iso-meshing. Isolux contours are curves of constant irradiance acrossasurface that can be followed using a predictor-corrector method based on the irradiance Jacobian. Similarly, local extrema can be found using a descent method. Finally, iso-meshing is a new approach to surface mesh generation that incorporates families of isolux contours. © ACM 1994.

关键词： Mesh generation

来源：评论

学校读者我要写书评

暂无评论

A model of visual masking for computer graphics 97

A model of visual masking for computer graphics

引用

24th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1997

作者： Ferwerda, James A. Shirley, Peter Pattanaik, Sumanta N. Greenberg, Donald P. Program of Computer Graphics Cornell University 580 Rhodes Hall Ithaca United States University of Utah United States

ISBN: (纸本)0897918967

In this paper we develop a computational model of visual masking based on psychophysical data. The model predicts how the presence of one visual pattern aects the detectability of another. The model allows us to choose texture patterns for computer graphics images that hide the eects of faceting, banding, aliasing, noise and other visual artifacts produced by sources of error in graphics algorithms. We demonstrate the utility of the model by choosing a texture pattern to mask faceting artifacts caused by polygonal tesselation of a flat-shaded curved surface. The model predicts how changes in the contrast, spatial frequency, and orientation of the texture pattern, or changes in the tesselation of the surface will alter the masking eect. The model is general and has uses in geometric modeling, realistic image synthesis, scientic visualization, image compression, and image-based rendering. Copyright © 1997 by the Association for Computing Machinery, Inc.

关键词： Image compression

来源：评论

学校读者我要写书评

暂无评论

A framework for the analysis of error In global illumination algorithms 94

A framework for the analysis of error In global illumination...

引用

21st Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1994

作者： Arvo, James Torrance, Kenneth Smits, Brian Program of Computer Graphics Cornell University 580 Engineering and Theory Center Building IthacaNY14853 United States

ISBN: (纸本)0897916670

In this paper we identify sources of error in global illumination algorithms and derive bounds for each distinct category. Errors arise from three sources: inaccuracies in the boundary data, discretization, and computation. Boundary data consist of surface geometry, reflectance functions, and emission functions, all of which may be perturbed by errors in measurement or simulation, or by simplifications made for computational efficiency. Discretization error is introduced by replacing the continuous radiative transfer equation with a finite-dimensional linear system, usually by means of boundary elements and a corresponding projection method. Finally, computational errors perturb the finite-dimensional linear system through imprecise form factors, inner products, visibility, etc., as well as by halting iterative solvers after a finite number of steps. Using the error taxonomy introduced in the paper we examine existing global illumination algorithms and suggest new avenues of research. © ACM 1994.

关键词： Linear systems

来源：评论

学校读者我要写书评

暂无评论

Effects of structural imperfections on constant-feedback-gain control of a spatial structure

引用

Computing Systems in Engineering 1990年第2-4期1卷 601-606页

作者： Aubert, B.H. Abel, J.F. Lu, J. Thorp, J.S. School of Civil and Environmental Engineering Program of Computer Graphics Cornell University Ithaca NY 14853 United States School of Electrical Engineering Cornell University Ithaca NY 14853 United States

The numerical sensitivity of a constant-feedback-gains controller to random structural imperfections is examined using the results of a series of finite element analyses. The basic finite element model, which uses linear beam-column elements, is a two-dimensional simplification of a large (10 m long) three-dimensional frame currently undergoing testing at cornell University. The cross-sectional properties, nodal coordinates, and masses of the models were randomly varied within four different ranges of maximum imperfection. Twenty transient dynamic analyses were run for each range of structural perturbation. Each analysis used a different random distribution of imperfections. The results of the finite element analyses show that the optimal control configuration, found by dynamic programming, exhibited unacceptable sensitivity to small perturbations of the structural model. A second, nearly optimal, control configuration was found to be more robust with respect to structural imperfections. © 1990.

关键词：

来源：评论

学校读者我要写书评

暂无评论

A model of visual adaptation for realistic image synthesis 96

A model of visual adaptation for realistic image synthesis

引用

23rd Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1996

作者： Ferwerda, James A. Pattanaik, Sumanta N. Shirley, Peter Greenberg, Donald P. Program of Computer Graphics 580 Frank H. T. Rhodes Hall Cornell University IthacaNY14853 United States

ISBN: (纸本)0897917464

In this paper we develop a computational model of visual adaptation for realistic image synthesis based on psychophysical experiments. The model captures the changes in threshold visibility, color appearance, visual acuity, and sensitivity over time that are caused by the visual system's adaptation mechanisms. We use the model to display the results of global illumination simulations illuminated at intensities ranging from daylight down to starlight. The resulting images better capture the visual characteristics of scenes viewed over a wide range of illumination levels. Because the model is based on psychophysical data it can be used to predict the visibility and appearance of scene features. This allows the model to be used as the basis of perceptually-based error metrics for limiting the precision of global illumination computations. © 1996 ACM.

关键词： Visibility

来源：评论

学校读者我要写书评

暂无评论

A reflectance model for computer graphics 81

A reflectance model for computer graphics

引用

8th Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1981

作者： Cook, Robert L. Torrance, Kenneth E. Program of Computer Graphics Cornell University IthacaNY14853 United States Sibley School of Mechanical and Aerospace Engineering Cornell University IthacaNY14853 United States

ISBN: (纸本)0897910451

This paper presents a new reflectance model for rendering computer synthesized images. The model accounts for the relative brightness of different materials and light sources in the same scene. It describes the directional distribution of the reflected light and a color shift that occurs as the reflectance changes with incidence angle. The paper presents a method for obtaining the spectral energy distribution of the light reflected from an object made of a specific real material and discusses a procedure for accurately reproducing the color associated with the spectral energy distribution. The model is applied to the simulation of a metal and a plastic. © 1981 ACM.

关键词： Reflection

来源：评论

学校读者我要写书评

暂无评论

Too many cooks don't spoil the broth: light simulation on massively parallel computers

Too many cooks don't spoil the broth: light simulation on ma...

引用

Frontiers of Massively Parallel Computation

作者： P. Kochevar Program of Computer Graphics Cornell University USA

A computer graphics algorithm for simulating the propagation of light and its interaction with matter on a massively parallel computer is presented. This algorithm, called the tagged shooting method, is designed for a virtual machine containing a great number of simple communicating processors arrayed into a cubical three-dimensional lattice. Only nearest neighbor communication among processors is assumed, and there is no reliance on global shared memory. The algorithm is similar in spirit to the classical progressive refinement radiosity method designed for more conventional computers but is not an adaptation of that technique to massive parallelism. Instead, the new algorithm uses a discretization of the wave equation as a local rule for shuttling radiant energy values between processors that correspond to regions of space. A number of example images that were created with an implementation of the algorithm on a Connection Machine are depicted and critiqued.< >

关键词： Computational modeling Concurrent computing Design methodology Algorithm design and analysis computer graphics computer simulation Optical propagation Virtual machining Lattices Nearest neighbor searches

来源：评论

学校读者我要写书评

暂无评论

Act: an easy-to-use and dynamically extensible 3D graphics library

Act: an easy-to-use and dynamically extensible 3D graphics l...

引用

Brazilian Symposium on computer graphics and Image Processing (SIBGRAPI)

作者： W. Celes J. Corson-Rikert Program of Computer Graphics Cornell University USA

The paper presents Act, an object oriented library for projects from specialized 3D graphics applications to simple interactive educational programs. Act meets the needs of both occasional and expert graphics programmers, offering a high level access to the OpenGL library and additional features including object creation, manipulation, and interaction. An interpreted language allows the Act library to be extended easily and dynamically.

关键词： programming profession computer graphics Layout Software libraries Graphical user interfaces Application software Educational programs Dynamic programming Rendering (computer graphics) Object oriented programming

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：