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Proceedings Paper

General physically-realistic BRDF models for computing stray light from arbitrary isotropic surfaces
Author(s): Alan W. Greynolds
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Paper Abstract

Proposed twenty-five years ago specifically for stray light computations, a general BRDF model that automatically enforces continuity, positivity, reciprocity, and isotropic surface symmetry over all possible input/output directions has been implemented in commercial optical analysis codes. It was originally motivated by the need to fit (and possibly catalogue) measured BRDFs of everything from polished optical surfaces to rough diffuse blacks, reasonably extend inplane only data to out-of-plane, reduce hundreds or thousands of measurement points to a relatively small number of parameters (like glass dispersion formulas), and cleanup “sloppy” data or models that violate physical constraints. However, there is little attempt to relate the BRDF to any actual surface structure or statistics (the inverse problem). As application examples, the model successfully fits several thousand measured data points on a “glossy” anodized Aluminum sample to a 100-coefficient form and several dozen measured data points on Aeroglaze Z306 diffuse black paint to a general 20-coefficient form then probably the simplest 2-parameter model. Variations and other general BRDF models are also proposed.

Paper Details

Date Published: 23 September 2015
PDF: 8 pages
Proc. SPIE 9577, Optical Modeling and Performance Predictions VII, 95770A (23 September 2015); doi: 10.1117/12.2185080
Show Author Affiliations
Alan W. Greynolds, Consultant (United States)

Published in SPIE Proceedings Vol. 9577:
Optical Modeling and Performance Predictions VII
Mark A. Kahan; Marie B. Levine-West, Editor(s)

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