# Resolve RDF Terms

$$\beta = \frac{L_n}{L_d}$$, where $$L_n$$ is the radiance of a surface element in a given direction and $$L_d$$ is the radiance of the perfect reflecting or transmitting diffuser identically irradiated and viewed. Reflectance factor is equivalent to radiance factor or luminance factor (when the cone angle is infinitely small, and is equivalent to reflectance when the cone angle is $$2π sr$$.
$$\beta$$