Modeling the BRDF from spectral reflectance measurements of metallic surfaces

The key quantity for expressing the directional optical effect of materials on the incident radiance is the bidirectional reflectance distribution function (BRDF). Our work is devoted to the BRDF spectral measurements, in order to render the synthetic images, mostly of the metallic paints. We measured the spectral reflectance off multiple paint samples then used the measured data to fit the analytical BRDF model, in order to acquire its parameters. Our contribution is in a mutual comparison and using the Cook-Torrance microfacet model as a fitting function for reflectance distribution evaluation. Results of analysis and the measurements were incorporated into the rendering process of car paint.