The material database provides broad coverage of common and more specialized materials, including isotropic and anisotropic BRDFs of metals, paper, car paints, organic samples, fabrics, etc. Each material is available in a spectral version that covers the 360(UV) - 1000nm (NIR) range with ~4nm sample spacing, as well as a RGB version for compatibility with renderers that do not support color spectra. The representation is extremely compact, requiring approximately 16KiB and 544KiB per channel for isotropic and anisotropic materials, respectively. Furthermore, it provides a natural importance sampling operation that does not require numerical fits or complex additional data structures. Technical details on the underlying parameterization and measurement methodology are available in the paper
An Adaptive Parameterization for Efficient Material Acquisition and Rendering (http://rgl.epfl.ch/publications/Dupuy2018Adaptive)