Bidirectional reflection functions from surface bump maps
The Torrance-Sparrow model for calculating bidirectional reflection functions contains a geometrical attenuation factor to account for shadowing and occlusions in a hypothetical distribution of grooves on a rough surface. Using an efficient table-based method for determining the shadows and occlusions, we calculate the geometric attenuation factor for surfaces defined by a specific table of bump heights. Diffuse and glossy specular reflection of the environment can be handled in a unified manner by using an integral of the bidirectional reflection function times the environmental illumination, over the hemisphere of solid angle above a surface. We present a method of estimating the integral, by expanding the bidirectional reflection coefficient in spherical harmonics, and show how the coefficients in this expansion can be determined efficiently by reorganizing our geometric attenuation calculation.
- Research Organization:
- California Univ., Davis (USA); Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6536916
- Report Number(s):
- UCRL-95910-Rev.1; CONF-870738-2-Rev.1; ON: DE87009618
- Resource Relation:
- Conference: ACM SIGGRAPH conference, Anaheim, CA, USA, 27 Jul 1987; Other Information: Paper copy only, copy does not permit microfiche production
- Country of Publication:
- United States
- Language:
- English
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