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NEW TECHNIQUES FOR FLAY TRACING PROCEDURALLY DEFINED OBJECTS

IP.com Disclosure Number: IPCOM000127938D
Original Publication Date: 1983-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 16 page(s) / 50K

Publishing Venue

Software Patent Institute

Related People

James T. Kajiya: AUTHOR [+3]

Abstract

We present new algorithms for efficient ray tracing of three procedurally defined objects: fractal sur-faces, prisms, and surfaces of revolution. The fractal sur-face algorithm performs recursive subdivision adaptively. Subsurfaces which cannot intersect a given ray are culled from further consideration. The prism algorithm trans-forms the three dimensional ray-surface intersection prob-lem into a two dimensional ray-curve intersection problem, which is solved by the method of strip trees. The surface of revolution algorithm transforms the three dimensional ray-surface intersection problem into a two dimensional curve-curve intersection problem, which again is solved by strip trees. KEYWORDS: computer graphics, raster graphics, ray tracing, fractal surfaces, procedural modelling, strip trees, stochastic models, surfaces of revolution. CR CATEGORIES: 1.3.3, 1.3.5, 1.3.7

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THIS DOCUMENT IS AN APPROXIMATE REPRESENTATION OF THE ORIGINAL.

NEW TECHNIQUES FOR FLAY TRACING PROCEDURALLY DEFINED OBJECTS

James T. Kajiya California Institute of Technology Pasadena, CA 91125

5098:TM:83

Published by ACM Computer Graphics, Volume 17, Number 3 July 1983. Pages 91-102. Computer Graphics - Volume 17, Number 3 - July 1983 NEW TECHNIQUES FOR RAY TRACING PROCEDURALLY DEFINED OBJECTS James T. Kajiya California Institute of Technology Pasadena, Ca. 9115

ABSTRACT.

We present new algorithms for efficient ray tracing of three procedurally defined objects: fractal sur-faces, prisms, and surfaces of revolution. The fractal sur-face algorithm performs recursive subdivision adaptively. Subsurfaces which cannot intersect a given ray are culled from further consideration. The prism algorithm trans-forms the three dimensional ray-surface intersection prob-lem into a two dimensional ray-curve intersection problem, which is solved by the method of strip trees. The surface of revolution algorithm transforms the three dimensional ray-surface intersection problem into a two dimensional curve-curve intersection problem, which again is solved by strip trees.

KEYWORDS: computer graphics, raster graphics, ray tracing, fractal surfaces, procedural modelling, strip trees, stochastic models, surfaces of revolution. CR CATEGORIES: 1.3.3, 1.3.5,
1.3.7

1 Introduction

Of all synthetic images, those rendered by ray tracing stand above the rest in realism (Appel[1], Goldstein and Nagle(10], Whitted(18]). Many have disparaged its use because of its large appetite for floating point computation. However - even though ray tracing is conceded to be the slowest of all methods for render-ing computer imagery - no other technique has a performance envelope quite as large. In ray trac-ing the combined effects of hidden surfaces, shadows, Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and/or specific permission.

ACM 0-89791-109-1/83/007/0091$00.75 reflection, and refraction are handled with a simplicity and elegance unmatched by its competitors.

This paper is about novel ways of performing the key computational step~in rendering procedural objects via ray tracing. We present new ways of computing the intersection between a ray and certain procedurally defined objects. The use of procedural objects is .not new to ray

California Institute of Technology Page 1 Dec 31, 1983

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NEW TECHNIQUES FOR FLAY TRACING PROCEDURALLY DEFINED OBJECTS

tracing - Whitted[16] and Rubin and Whitted[15] have advocated their use. Indeed, one could make the claim that the natural organization for ray tracing programs is one using procedural ob...