authors 
Westin, S., Arvo, J. and Torrance, K. 
year 
1992 
title 
Predicting reflectance functions from complex surfaces 
source 
Computer Graphics, 26(2):255264, July 1992 
summary 
We describe a physicallybased Monte Carlo technique for approximating bidirectional re•ectance distribution functions (BRDFs) for a large class of geometries by directly simulating optical scattering. The technique is more general than previous analytical models: it removes most restrictions on surface microgeometry. Three main points are described: a new representation of the BRDF, a Monte Carlo technique to estimate the coef•cients of the representation, and the means of creating a milliscale BRDF from microscale scattering events. These allowthe prediction of scattering from essentially arbitrary roughness geometries. The BRDF is concisely represented by a matrix of spherical harmonic coef•cients; the matrix is directly estimated from a geometric optics simulation, enforcing exact reciprocity. The method applies to roughness scales that are large with respect to the wavelength of light and small with respect to the spatial density at which the BRDF is sampled across the surface; examples include brushed metal and textiles. The method is validated by comparing with an existing scattering model and sample images are generated with a physicallybased global illumination algorithm. 
series 
journal paper 
full text 
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references 
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last changed 
2003/04/23 13:50 
