Photorealism in 3D rendering is expanding across different fields of applications, including 3D games industry and rapid prototyping in many domains already in early design stages, e.g. in the automotive and textile industry. But where do the specifications come from that define realistic materials? Manual design of material models has been perfected over a long time to deliver quite good results. The only way, however, to bring out the physically correct light interaction behavior for each individual (or mixture of different) material(s) on a surface, is actual measurement under systematic illumination from a set of different perspectives to reveal the actual optical reaction. One reason to go this far is material behavior faithful to reality, and individual rather than defining abstract classes of materials. Another reason is damage assessment, e.g. for industrial quality control.