Comment on “Current definitions of reflectance”

The delta-function form of the bidirectional reflectance-distribution function (BRDF) is not limited to the case where θv = θi and ψv = ψi ± π (rad), but can represent a “glint” in any direction. The conceptual advantage of the BRDF approach is briefly discussed in relation to the continuum of directional distributions actually found between the limits of purely specular “spikes” and completely diffuse reflection.