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A-BUFFER, AN ANTIALIASED HIDDEN SURFACE METHOD.

computer graphics (ACM) 1984年第3期18卷 103-108页

作者： Carpenter, Loren Lucasfilm Ltd Computer Graphics Project San Rafael CA USA Lucasfilm Ltd Computer Graphics Project San Rafael CA USA

ISBN: (纸本)0897911385

The A-buffer (anti-aliased, area-averaged, accumulation buffer) is a general hidden surface mechanism suited to medium scale virtual memory computers. It resolves visibility among an arbitrary collection of opaque, transparent, and intersecting objects. Using an easy to compute Fourier window (box filter), it increases the effective image resolution many times over the Z-buffer, with a moderate increase in cost. The A-buffer is incorporated into the REYES 3-D rendering system at Lucasfilm and was used successfully in the 'Genesis Demo' sequence in Star Trek II.

关键词： Surfaces

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PLANTS, FRACTALS, AND FORMAL LANGUAGES.

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computer graphics (ACM) 1984年第3期18卷 1-10页

作者： Smith, Alvy Ray Lucasfilm Ltd Computer Graphics Project San Rafael CA USA Lucasfilm Ltd Computer Graphics Project San Rafael CA USA

ISBN: (纸本)0897911385

Although fractal models of natural phenomena have received much attention recently, there are other models of complex natural objects which have been around longer in computer Imagery but are not widely known. These are procedural models of plants and trees. An interesting class of these models is presented here which handles plant growth, sports an efficient data representation, and has a high 'database amplification' factor. It is based on an extension of the well-known formal languages of symbol strings to the lesser-known formal languages of labeled graphs. It is so tempting to describe these plant models as 'fractal' that the similarities of this class of models with fractal models are explored in an attempt at rapprochement The models are not fractal so the common parts of fractal theory and plant theory are abstracted to form a class of objects, the graftals. This class may prove to be of great interest to the future of computer Imagery. Determinism is shown to provide adequate complexity, whereas randomness is only convenient and often inefficient. Finally, a nonfractal, nongraftal family of trees by Bill Reeves is introduced to emphasize some of the nongrammatical themes.

关键词： Automata theory

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COMPOSITING DIGITAL IMAGES.

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computer graphics (ACM) 1984年第3期18卷 253-259页

作者： Porter, Thomas Duff, Tom Lucasfilm Ltd Computer Graphics Project San Rafael CA USA Lucasfilm Ltd Computer Graphics Project San Rafael CA USA

ISBN: (纸本)0897911385

Most computer graphics pictures have been computed all at once, so that the rendering program takes care of all computations relating to the overlap of objects. There are several applications however, where elements must be rendered separately, relying on compositing techniques for the anti-aliased accumulation of the full image. This paper presents the case for four-channel pictures, demonstrating that a matte component can be computed similarly to the color channels. The paper discusses guidelines for the generation of elements and the arithmetic for their arbitrary compositing.

关键词： computer graphics

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The A -buffer, an antialiased hidden surface method 84

The A -buffer, an antialiased hidden surface method

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Proceedings of the 11th annual conference on computer graphics and interactive techniques

作者： Loren Carpenter Computer Graphics Project Computer Division Lucasfilm Ltd

ISBN: (纸本)9780897911382

关键词： Antialiasing computer imagery Z-buffer Hidden surface Image synthesis Supersampling Transparency A-buffer

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Chap - a SIMD graphics processor 84

Chap - a SIMD graphics processor

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Proceedings of the 11th annual conference on computer graphics and interactive techniques

作者： Adam Levinthal Thomas Porter Computer Graphics Project Lucasfilm Ltd.

ISBN: (纸本)9780897911382

Special purpose processing systems designed for specific applications can provide extremely high performance at moderate cost. One such processor is presented for executing graphics and image processing algorithms as the basis of a digital film printer. Pixels in the system contain four parallel components: RGB for full color and an alpha channel for retaining transparency information. The data path of the processor contains four arithmetic elements connected through a crossbar network to a tessellated scratchpad memory. The single instruction, multiple data stream (SIMD) processor executes instructions on four pixel components in parallel. The instruction control unit (ICU) maintains an activity stack for tracking block-structured code, using data-dependent activity flags for conditional disabling subsets of the ALUs. Nested loops and if-then-else constructs can be programmed directly, with the ICU disabling and reenabling ALUs on the basis of their individual status bits.

关键词： computer graphics Parallel processing Digital film printers SIMD architecture Compositing Tesselation

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Plants, fractals, and formal languages 84

Plants, fractals, and formal languages

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Proceedings of the 11th annual conference on computer graphics and interactive techniques

作者： Alvy Ray Smith Computer Graphics Project Computer Division Lucasfilm Ltd.

ISBN: (纸本)9780897911382

Although fractal models of natural phenomena have received much attention recently, there are other models of complex natural objects which have been around longer in computer Imagery but are not widely known. These are procedural models of plants and trees. An interesting class of these models is presented here which handles plant growth, sports an efficient data representation, and has a high “database amplification” factor. It is based on an extension of the well-known formal languages of symbol strings to the lesser-known formal languages of labeled graphs. It is so tempting to describe these plant models as “fractal” that the similarities of this class of models with fractal models are explored in an attempt at rapprochement. The models are not fractal so the common parts of fractal theory and plant theory are abstracted to form a class of objects, the graftals. This class may prove to be of great interest to the future of computer Imagery. Determinism is shown to provide adequate complexity, whereas randomness is only convenient and often inefficient. Finally, a nonfractal, nongraftal family of trees by Bill Reeves is introduced to emphasize some of the paper's nongrammatical themes.

关键词： L-system Parallel graph grammar Fractal Graftal Plant Tree computer imagery Particle system Database amplification

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Compositing digital images 84

Compositing digital images

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Proceedings of the 11th annual conference on computer graphics and interactive techniques

作者： Thomas Porter Tom Duff Computer Graphics Project Lucasfilm Ltd. AT&T Bell Laboratories Murray Hill NJ

ISBN: (纸本)9780897911382

Most computer graphics pictures have been computed all at once, so that the rendering program takes care of all computations relating to the overlap of objects. There are several applications, however, where elements must be rendered separately, relying on compositing techniques for the anti-aliased accumulation of the full image. This paper presents the case for four-channel pictures, demonstrating that a matte component can be computed similarly to the color channels. The paper discusses guidelines for the generation of elements and the arithmetic for their arbitrary compositing.

关键词： Compositing

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The challenge of CAD/CAM education 82

The challenge of CAD/CAM education

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Proceedings of the 9th annual conference on computer graphics and interactive techniques

作者： Michel A. Melkanoff Frank Puhl Victor Langer Donald P. Greenberg Mark S. Shepard Herb Voelcker UCLA President CADAM Inc. Computer Graphics Project Director Milwaukee Area Technical College Director Program of Computer Graphics Cornell University Rensselaer Polytechnic Institute Production Automation Project University of Rochester

ISBN: (纸本)9780897910767

Colleges and universities are not meeting industry needs for graduates trained in the use or implementation of computer-aided design and manufacturing systems since few schools have experience in teaching CAD/CAM. Furthermore, many Bachelor's-level graduates are going directly into industry, rather than pursuing graduate degrees, thereby compounding this problem. Members of this panel represent both schools and industry and together attempt to outline approaches to developing more extensive CAD/CAM emphasis in education, including- the role colleges and universities can or should play in addressing industry needs in this area- user- and implementor-oriented CAD/CAM education- CAD/CAM education as an integral part of university engineering curricula- problems encountered in organizing and implementing CAD/CAM curriculum- universities' relationships with *** is our hope that panelists' experiences will help guide schools in structuring CAD/CAM programs to best insure that the United States remain at the forefront of technology and compete industrially *** PuhlVictor LangerDonald P. GreenbergMark S. ShepardHerb VoelckerUniversities' Relationships With IndustryFrank PuhlAmerican industry needs engineers who have been brought up with the realization that computers are intimately involved in all aspects of design, analysis, and manufacturing. Industry, of course, needs engineers who are already trained in fundamental CAD/CAM principles and in solving real world problems using computers, as well as those who have been taught to be productivity- and *** help meet these needs, we must now provide answers to several significant questions:What part should industry play in encouraging and sponsoring research and education in CAD/CAM?How can we resolve conflicts between industries' “trade secrets” and universities' “open research”?How can industry and educational institutions work together to increase U.S. productivity so as to regain our compe

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Towards a laboratory instrument for motion analysis 81

Towards a laboratory instrument for motion analysis

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

作者： Baecker, Ronald Miller, David Reeves, William Dynamic Graphics Project Department of Computer Science Computer Systems Research Group University of Toronto TorontoON Canada Human Computing Resources Corporation Toronto Canada Micom Co. Montreal Canada Sprocket Systems Lucasfilm San AnselmoCA United States

ISBN: (纸本)0897910451

Motion analysis is the systematic and usually quantitative study of the movements of humans, animals, organisms, cells, or other entities as recorded on movie film or video tape. Despite the utility of computer-aided motion analysis to many biological, social, and physical sciences, its role has been limited because it is so time-consuming and so expensive. Automated techniques can only be used-on real images in very special cases;interactive techniques have involved laborious frame by frame operations. In recent years, Futrelle and Potel have revolutionized the process of interactive motion analysis by demonstrating how to digitize entire motions with a single sketch rather than with a sequence of operations on each constituent frame. However, their GALA-TEA system is applicable only to film and not to video tape records, and consists of equipment which cannot easily be engineered into a reliable and mass-producible laboratory instrument. The paper describes a prototype laboratory instrument for the interactive motion analysis of video tape records. The prototype includes a host PDP 11/45 computer, an experimental display processor called SPIWRIT, and a microprocessor-controlled video disk. SPIWRIT generates a computer-animated video representation of the phenomenon being analysed, and superimposes it on the actual video record being streamed from the video disk. SPIWRIT's bit-slice microprogrammable display processor produces true animation on a colour raster display by decoding segmented display file images into alternate halves of a double frame buffer. © 1981 ACM.

关键词： Motion analysis

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A ccnversational extensible system for the animation of shaded images 3

A ccnversational extensible system for the animation of shad...

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3rd Annual Conference on computer graphics and Interactive Techniques, SIGGRAPH 1976

作者： Baecker, Ronald M. Computer Systems Research Group Dynamic Graphics Project University of Torcnto TorontoON Canada

The terms "conversational" and "extensible" are defined and shown to be useful properties of computer animation systems. A conversational extensible system for the animation of shaded images is then described. With this system, implemented on a minicomputer, the animator can sketch images and movements freehand, or can define them algorithmically via the Smalltalk language. The system is itself implemented in Smalltalk, and hence can be easily extended or mcdified to suit the animator's personal style.

关键词： Animation

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