In this tutorial we'll examine photon mapping in V-Ray and efficient ways
to use it.
Photon mapping is a technique for computing global illumination. However,
in difference from the irradiance map, which starts tracing rays from the
camera, photon mapping traces rays from the lights in the scene. The two
approaches are not mutually exclusive, and indeed for best results the
photon map and the irradiance map should be used together.
The photon map has many parameters that allow for a lot of interesting
results; here we will not discuss all possibilities but will just point out
settings that are reliable and work well in most cases.