Most surfaces, including most fabrics, have different reflectance at different points on the surface. The reflectance also varies based on the incident and exitant light directions. This spatially and angularly varying surface appearance is a 6D function, sometimes called the Spatial Bi-directional Reflectance Distribution Function (SBRDF). We present a system for measuring the SBRDF of real fabrics in a lab setting. Our system is able to capture distinct anisotropic BRDFs at each point on the fabric.
The measurement device yields from 300 MB to 8 GB of reflectance data for complex fabrics. We compress the SBRDF using a sum of very few nonlinear bases suited to BRDFs, yielding a highly compact texture map of from 2 to 20 MB, suitable for accurately visualizing articles made of specific fabrics interactively using commodity graphics hardware. We provide an online database of sampled SBRDFs, both in raw form and as final texture maps.
