Light reflection model for lighting applications

This work is intended to propose a mathematical model to describe the scattering indicatrix of light reflected by several materials. Surface reflection is modelled by two terms: one for the coherent (specular) contribution and the second for the incoherent contribution, depending on the roughness of the surface. The volume or bulk reflection is represented by a modified Lambert law, which is added to the surface components to form the general model for light reflection. This is a five-parameter model which expresses the angular variation of the luminance factor. It has been tested for several materials and compared with measurements and other models.