<title>Diffuse reflectance model for dielectric surfaces</title>

Abstract

One of the most common assumptions for recovering object features in computer vision and rendering objects in computer graphics is that the radiance distribution of diffuse reflection from materials in Lambertian. We propose a reflectance model for diffuse reflection from smooth inhomogeneous dielectric surfaces that is empirically shown to be significantly more accurate than the Lambertian model. The resulting reflected diffuse radiance distribution has a simple mathematical form. The proposed model for diffuse reflection utilizes results of radiative transfer theory for subsurface multiple scattering. For an optically smooth surface boundary this subsurface intensity distribution becomes altered by Fresnel attenuation and Snell refraction making it become significantly non-Lambertian. We present a striking diffuse reflection effect at occluding contours of dielectric objects that is strongly deviant from Lambertian behavior, and yet is explained by our diffuse reflection model. The proposed diffuse reflection model for optically smooth surfaces can be used to describe diffuse reflection from rough dielectric surfaces by serving as the diffuse reflection law for optically smooth microfacets.