Accurate Physics-Based Polarimetric BRDF

Scattering from surfaces continue to be an important area of research where both accuracy and ease of use are needed. Surface properties of interest vary from diffuse (Lambertian) to specular (mirror). The effort here is to, based on and guided by basic physical optics, derive a limited set of rather accurate models that can be used for the majority of materials by only varying a set of parameters. The two basic models are addressing the scattering from Lambertian type surfaces with a correlation length shorter than the wavelength, here called diffuse surfaces and from surfaces with a correlation length of the order of the wavelength or longer, here called rough surfaces. These two basic models cover a large class of surfaces. Thus, in most cases only two BRDF functions have to be used, which makes the modelling and the simulations very efficient. If the diffuse part of scattering can be approximated with the Lambertian approach, then only the rough part of the surface scattering description requires a more sophisticated model. The scattering properties of the rough surface can be calculated using two lookup vectors and one lookup table. The lookup vectors are connected to the Fresnel s- and p-polarized reflectance and the lookup table is connected to the angular spread function. In some cases, the angular spread function can be also characterized by a vector. These features should make the model attractive for simulations and other computationally intense applications.