A useful way to present scatter data is scattered light power density (dPs/dws) normalized by the incident light power and plotted as a function of angle from specular. Nicodemus pointed out that if this quantity is also normalized by the cosine of the angle between the surface normal and the direction of scatter (Os) that the resulting expression was the differential scattered radiance normalized by the incident irradiance. This expression has become known as the bidirectional scattered (reflectance or transmission) distribution function (BSDF, BRDF or BTDF).
© (1987) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Daniel R. Cheever ; Fredrick M. Cad ; Kyle A. Klicker and John C. Stover
Design Review Of A Unique Complete Angle Scatter Instrument (CASI)
", Proc. SPIE 0818, Current Developments in Optical Engineering II, 13 (January 1, 1987); doi:10.1117/12.978542; http://dx.doi.org/10.1117/12.978542