2008

Global illumination made smoother by final gather
To calculate global illumination, the mental ray renderer uses the
photon
map technique
on page 7894 .
NOTE The mental ray renderer generates global illumination without requiring
you to generate a radiosity solution. A photon map is a model of global illumination
in its own right.
NOTE In order to use global illumination in mental ray, the photons must be able
to bounce among two or more surfaces. This can be accomplished by having a
single object with some concavity in its surface that’s exposed to the light source,
or at least two objects, and at least one object must be set to receive global
illumination (see
mental ray Panel (Object Properties Dialog) on page 262 ).
Otherwise you’ll receive error messages and no photons will be stored.
Using a photon map can cause rendering artifacts such as dark corners and
low-frequency variations in the lighting. You can reduce or eliminate these
artifacts by turning on
final gathering on page 6104 , which increases the number
of rays used to calculate global illumination.
You enable global illumination on the Render Scene dialog > Indirect
Illumination panel >
Caustics And Global Illumination rollout on page 6096 ,
mental ray Renderer | 6075