15-4 From Surface Roughness to Surface Displacements

This paper presents an extension to a measurement system to capture bidirectional refEectance distribution function (BRDF) values and texture maps out of images. The extension will enable the measurement of reflection effects due to surface roughness and additionally extracts a map representing local surface displacements. Different lighting conditions where used to discriminate between surface roughness and bump mapping which both result in variations of gathered reflected intensity. Experimental results will show the potential of the measurement system to capture complex reflectance characteristics, texture as well as bump maps from a set of few images. Local geometric deformations of the samples are therefore not restricted to a microscopic scale and samples with much coarser variations in surface geometry can be captured. The resulting material description has an important impact on computer graphics applications targeted on photorealism. Using recent graphics accelerators which can handle per-pixel lighting and bump mapping even photorealistic realtime renderings are feasible.