Extinction and Scattering Coefficient Ray Tracing for Global Illumination

Lecture 24 defines the extinction coefficient, scattering coefficient and albedo, derives the differential equation for radiance transport in a participating medium, shows how to create a photon map for a participating medium and how to integrate its inscattering along a viewing ray. (At 12 minutes "d omega" should be "d omega' ". The end of the bidirectional path tracing discussion should have included a factor of the transparency along the dotted line.)