Abstract
Many optical reflection models have been proposed in computer-vison and computer-graphics. Parameters contained in the models are frequently determined in empirical ways. High sensitivity of data to experimental conditions makes it difficult to formulate the parameters. In order to compare the results between many experiments, a generally usable standard of radiance must be extracted in each of experiment. We proposed a method of estimating normal diffuse radiance (NDR) of cuboids' surface, i.e., radiance of a normally illuminated surface, without accurately adjusting the surface direction toward ligth source. This paper deals with a reflection model at a rounded edge of cuboids by using the NDR as a standard of radiance and gets following results. (1) The diffuse radiance at a rounded edge is well approximated by a function of cos2 φ where φ is an incident angle. (2) By using the NDR, a relation between diffuse radiance of an edge and those of surfaces of cuboids can be quantitatively formulated. (3) Theoretical results (1) and (2) are examined by experiments and are validated.
