This paper proposes a practical method for the tabulation and completion of measured BRDF data. The BRDF of materials is needed for lighting computations and computer graphics. It can be measured with a gonioreflectometer, but the resulting data is often irregular and always partial. A common solution to get a complete BRDF is to fit the available data with an analytical model. An arguably more accurate solution is to interpolate and extrapolate from the available data. This solution was implemented using Scilab, a free open-source software, and tested on two typical road surface materials: plain asphalt pavement and asphalt pavement painted with retroreflective marking.
