A coupled matte-specular reflection model

Real surfaces often exhibit both specular (mirror-like) and matte behavior. In many scientific fields this behavior is approximated by the “Lambertian-specular ” model, where a linear combination of Lambertian and ideal specular reflection is assumed. While this approximation is useful, it does not capture the dramatic surface appearance for acute and near-perpendicular viewing angles. The model presented in this paper does capture these angle-dependent behavior changes by allowing the matte and specular coefficients to co-vary. Furthermore, this modified matte-specular model uses a non-Lambertian matte term to maintain reciprocity of the bidirec-tional reflectance distribution function (BRDF), an important point for many rendering engines. Finally, this model maintains the sim-plicity of the traditional models. An associated web page i