Accession Number : ADA324608

Title :   Simulating Soft Shadows with Graphics Hardware,

Corporate Author : CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF COMPUTER SCIENCE

Personal Author(s) : Heckbert, Paul S. ; Herf, Michael

PDF Url : ADA324608

Report Date : 15 JAN 1997

Pagination or Media Count : 10

Abstract : This paper describes all algorithm for simulating soft shadows at interactive rates using graphics hardware. On current graphics workstations, the technique can calculate the soft shadows cast by moving, complex objects onto multiple planar surfaces in about a second. In a static, diffuse scene, these high quality shadows can then be displayed at 30 Hz, independent of the number and size of the light sources. For a diffuse scene, the method precomputes a radiance texture that captures the shadows and other brightness variations on each polygon. The texture for each polygon is computed by creating registered projections of the scene onto the polygon from multiple sample points on each light source, and averaging the resulting hard shadow images to compute a soft shadow image. After this precomputation, soft shadows in a static scene can be displayed in real time with simple texture mapping of the radiance textures. All pixel operations employed by the algorithm are supported in hardware by existing graphics workstations. The technique can be generalized for the simulation of shadows on specular surfaces.

Descriptors :   *COMPUTERIZED SIMULATION, *SHADOWS, *POLYGONS, ALGORITHMS, REAL TIME, INTERACTIONS, RATES, VARIATIONS, SURFACES, BRIGHTNESS, LIGHT SOURCES, RADIANCE, IMAGES, PLANAR STRUCTURES, COMPUTER GRAPHICS, WORK STATIONS, DIFFUSION, MAPPING, STATICS, TEXTURE, SPECULAR REFLECTION.

Subject Categories : Computer Programming and Software
      Cybernetics

Distribution Statement : APPROVED FOR PUBLIC RELEASE