A modified version of BRDF model based on Kubelka-Munk theory for coating materials

The bidirectional reflectance distribution function (BRDF) can characterize the general optical property of object's surface. The conventional BRDF model that a Lambertian constant volume scattering consideration has the limitation for the description of scattering characteristic of coating materials. Thus, a modified version of BRDF model is presented for coating materials with considering specular reflection and volume scattering based on the combination of the microfacet and Kubelka-Munk (K-M) theory. In this model, a mirror parameter, related to the surface roughness and reflectance, is introduced to adjust this model, and the volume scattering component is modeled following the K-M theory to make this new BRDF model more correspondence with physical interpretation. The simulation and measurement results for three kinds of coating samples show that the BRDF values simulated by the modified BRDF model are found in a good agreement with the measurements, and the model presented in this paper can improve the modeling accuracy effectively, which provides the theoretical support for remote sensing.