Comparing Variants of the Beckmann Model

Abstract Recent work has shown how the Fresnel coefficient can be used to improve the predictions of the Beckmann-Kirchhoff (BK) model for moderatelyrough surfaces. This paper aims to compare the predictions of a number of alternative models including those of Lafortune et al. (LFTG) and Oren-Nayar (ON) against the BRDF measurements from the CUReT database. Excluding the specular reflectance component, we explore how these models account for the diffuse reflectance component. Our main conclusions are as follows. First, for moderately rough samples Fresnel correction provides the most accurate predictions for the majority of the samples studied. Second, although there are several surface samples in the CUReT database for which the ON model provides the best fit, the ON model and the LFTG model fail to fit the data well for most of the surface samples. Third, for all surface samples studied, the Fresnel corrected variant of the BK model gives more realistic predictions than the empirical reflectance models such as the LFTG model.