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COLLISION DETECTION FOR INTERACTIVE graphics APPLICATIONS

IEEE TRANSACTIONS ON VISUALIZATION AND computer graphics 1995年第3期1卷 218-230页

作者： HUBBARD, PM Program of Computer Graphics Cornell University Ithaca NY USA

Collision detection and response are important for interactive graphics applications such as vehicle simulators and virtual reality. Unfortunately, previous collision-detection algorithms are too slow for interactive use. This paper presents a new algorithm for rigid or articulated objects that meets performance goals through a form of time-critical computing. The algorithm supports progressive refinement, detecting collisions between successively tighter approximations to object surfaces as the application allows it more processing time. The algorithm uses simple four-dimensional geometry to approximate motion, and hierarchies of spheres to approximate three-dimensional surfaces at multiple resolutions. In a sample application, the algorithm allows interactive performance that is not possible with a good previous algorithm. In particular, the new algorithm provides acceptable accuracy while maintaining a steady and high frame rate, which in some cases improves on the previous algorithm's rate by more than two orders of magnitude.

关键词： COLLISION DETECTION TIME-CRITICAL COMPUTING REAL-TIME PERFORMANCE INTERACTION 4 DIMENSIONS APPROXIMATION

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TEXTURES FOR REALISTIC IMAGE SYNTHESIS

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computerS & graphics 1985年第2期9卷 125-&页

作者： CAREY, RJ GREENBERG, DP Program of Computer Graphics Cornell University Ithaca NY 14853 USA

An important aspect in generating images of real materials and surfaces is the contribution of the visual effects of textures. This study presents methods for simulating a variety of different textures. Two general types of texture, geometric and spectral, are simulated. Geometric textures incorporate the irregularities and variations which can be found in the shape and form of real surfaces. Spectral textures involve variations of the properties of materials which cause the absorption of specific wavelengths of light. An integrated system for image synthesis which is based on ray tracing is used as the testbed for the texturing research. Previous methods of texturing are adapted by ray tracing, and some new methods for simulating heterogeneous materials are presented.

关键词： computer graphics

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UNIFIED INTERACTIVE GEOMETRIC MODELER FOR SIMULATING HIGHLY COMPLEX ENVIRONMENTS (REPRINTED FROM KNOWLEDGE ENGINEER AND computer MODELING IN CAD, 1986)

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computer-AIDED DESIGN 1986年第10期18卷 539-545页

作者： BROCK, PJ POLINSKY, AJ SLIVKA, R GREENBERG, DP Program of Computer Graphics 120 Rand Hall Cornell University Ithaca NY 14853 USA

The advent of supercomputer technology has greatly increased the power available to process and analyse larger and more complex geometric models than are currently in use. A comprehensive experimental geometric modelling system is presented, which exploits this new technology by allowing for the description of highly complex environments, providing flexible creation and editing facilities, and introducing the capability to model dynamic environments. The system interfaces to various shading and realistic image synthesis routines, and attempts to overcome the restrictions of current display technology. Close attention is paid to the user interface so as not to limit interaction to any particular modelling methodology. To this end, a variety of geometries, an expandable set of object generation routines, and many geometric editing tools are supported. Hierarchical and adjacency associations are also definable between the elements in an environment. To provide a means for dynamic simulation, tools to define object motion are also provided. Environment descriptions are organized into a partitioned database, composed of hierarchical and relational data constructs, allowing for selective subdivision of a complex model into component units and efficient database management.

关键词： computer-aided design computer graphics supercomputers geometric modelling user interface

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A visible polygon reconstruction algorithm

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ACM Transactions on graphics 1982年第1期1卷 25-42页

作者： Sechrest, Stuart Greenberg, Donald P. Program of Computer Graphics Cornell University IthacaNY14853 United States

An algorithm for determining visible lines or visible surfaces in polygonal form, at object resolution, is presented. The original scene must consist of nonintersecting planar polygons. The procedure relies on image coherence, since the sampling is dependent on the complexity of the image. The reconstruction method is based on an elaborate data structure, which allows the polygonal output to be easily obtained. The polygonal output is useful for smooth shaded or textured images, as well as for the creation of shadows. © 1982 ACM.

关键词： Interactive computer graphics

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DETERMINING A SET OF B-SPLINE CONTROL VERTICES TO GENERATE AN INTERPOLATING SURFACE

COMPUTER GRAPHICS AND IMAGE PROCESSING

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computer graphics AND IMAGE PROCESSING 1980年第3期14卷 203-226页

作者： BARSKY, BA GREENBERG, DP Program of Computer Graphics Cornell University Ithaca New York 14853 USA

It is desirable to be able to use the B-spline surface formulation to describe a surface initially defined by a completely specified network of points to be interpolated. An appropriate set of B-spline control vertices which will generate an interpolating surface can be determined by solving a set of simultaneous linear equations. These equations are derived, efficient algorithms are designed to solve them rapidly, and the implementation of this theory in a computer-aided geometric design system is presented.

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TEXTURE RENDERING SYSTEM FOR ARCHITECTURAL DESIGN

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computer-AIDED DESIGN 1980年第2期12卷 67-71页

作者： FEIBUSH, E GREENBERG, DP Program of Computer Graphics Cornell University Ithaca NY 14853 USA

Depicting construction materials in colour enhances the realism of synthetic images and provides the architect with a powerful design tool. A computer-aided system for creating textured renderings of architectural designs is presented. This enables the designer to organize libraries of texture samples and details extracted from digital images of colour photographs of actual materials. Furthermore, buildings can be interactively positioned on an optically scanned site background and the textures mapped to simulate any desired view of the building. The system was designed so that it could be used quickly and easily by architects with little computer experience.

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Computation of higher order illumination with a non-deterministic approach

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computer graphics FORUM 1996年第3期15卷 C327-&页

作者： Bouatouch, K Pattanaik, SN Zeghers, E IRISA Campus de Beaulieu 35042 Rennes Cedex France Program of computer graphics Cornell university

In spite of the number of efforts made by the computer graphics researchers, till today the computation of view-independent global illumination in an environment containing non-diffusely reflecting objects is a non-resolved problem. In general non-deterministic techniques seem to be capable of solving this problem. In this article we propose one such non-deterministic method which will permit such calculation by using a combined technique of higher order function approximation and particle tracing. We have used multi-wavelets as basis functions and have calculated the illumination function approximation coefficients;by exploiting the adjointness between the radiance equation and the potential equation.

关键词： radiance equation potential equation adjointness Monte Carlo quadrature random walk particle tracing weighted function approximation multiwavelet push/pull operation

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Bounds and error estimates for radiosity 94

Bounds and error estimates for radiosity

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Proceedings of the Annual Conference on computer graphics

作者： Lischinski, Dani Smits, Brian Greenberg, Donald P. Program of Computer Graphics Cornell University

ISBN: (纸本)9780897916677

We present a method for determining a posteriori bounds and estimates for local and total errors in radiosity solutions. The ability to obtain bounds and estimates for the total error is crucial fro reliably judging the acceptability of a solution. Realistic estimates of the local error improve the efficiency of adaptive radiosity algorithms, such as hierarchical radiosity, by indicating where adaptive refinement is ***, we describe a hierarchical radiosity algorithm that computes conservative lower and upper bounds on the exact radiosity function, as well as on the approximate solution. These bounds account for the propagation of errors due to interreflections, and provide a conservative upper bound on the error. We also describe a non-conservative version of the same algorithm that is capable of computing tighter bounds, from which more realistic error estimates can be obtained. Finally, we derive an expression for the effect of a particular interaction on the total error. This yields a new error-driven refinement strategy for hierarchical radiosity, which is shown to be superior to brightness-weighted refinement.

关键词： importance hierarchical radiosity global illumination adaptive refinement a posteriori error bounds and estimates

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Simulating multiple scattering in hair using a photon mapping approach 06

Simulating multiple scattering in hair using a photon mappin...

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ACM SIGGRAPH 2006

作者： Moon, Jonathan T. Marschner, Stephen R. Program of Computer Graphics Cornell University

ISBN: (纸本)9781595933645

Simulating multiple scattering correctly is important for accurate rendering of hair. However, a volume of hair is a difficult scene to simulate because scattering from an individual fiber is very structured and forward directed, and because the radiance distributions that arise from many such scattering events remain quite directional. For these reasons, previous methods cannot compute accurate images substantially faster than Monte Carlo path tracing. This paper proposes a new physically accurate method for rendering hair that is based on previous volumetric photon mapping methods. The first pass generates a photon map by tracing particles through the hair geometry, depositing them along paths rather than at scattering events. The second pass ray traces the hair, computing direct illumination and looking up indirect radiance in the photon map. Photons are stored and looked up in 5D position-direction space to allow for the very directional radiance distributions that occur in hair. Together with a new radiance caching method for fibers, our method simulates difficult scattering problems in hair efficiently and with low noise. The new algorithm is validated against path tracing and also compared with a photograph of light scattering in real hair. Copyright © 2006 by the Association for Computing Machinery, Inc.

关键词： Light scattering

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Fitting virtual lights for non-diffuse walkthroughs 97

Fitting virtual lights for non-diffuse walkthroughs

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

作者： Walter, Bruce Alppay, Gün Lafortune, Eric Fernandez, Sebastian Greenberg, Donald P. Cornell Program of Computer Graphics United States

ISBN: (纸本)0897918967

This paper describes a technique for using a simple shading method, such as the Phong lighting model, to approximate the appearance calculated by a more accurate method. The results are then suitable for rapid display using existing graphics hardware and portable via standard graphics API's. Interactive walkthroughs of view-independent nondi. use global illumination solutions are explored as the motivating application. Copyright © 1997 by the Association for Computing Machinery, Inc.

关键词： Interactive computer graphics

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