Editing Rendering (computer graphics) (section)

=== The bidirectional reflectance distribution function ===
The '''[[bidirectional reflectance distribution function]]''' (BRDF) expresses a simple model of light interaction with a surface as follows:

: <math>f_r(x, \omega', \omega) = \frac{\mathrm d L_r(x, \omega)}{L_i(x, \omega')(\omega' \cdot \vec n) \mathrm d \omega'}</math>

Light interaction is often approximated by the even simpler models: diffuse reflection and specular reflection, although both can ALSO be BRDFs.