2008

Max. Reflections Sets the number of times a photon can be reflected. At 0,
no reflection occurs. At 1, the photon can be reflected once only. At 2, the
photon can be reflected twice, and so on. Default=5.
Max. Refractions Sets the number of times a photon can be refracted. At 0,
no refraction occurs. At 1, the photon can be refracted once only. At 2, the
photon can be refracted twice, and so on. Default=5.
Light Properties group
Controls in this group affect how lights behave when calculating indirect
illumination. By default, the energy and photon settings apply to all lights in
a scene. Use the
mental ray Indirect Illumination rollout on page 5060 for light
objects to adjust an individual light either by multiplying the global values,
or by setting local values (using multipliers is the recommended method).
Average Caustic Photons per Light Sets the number of photons emitted by
each light for use in caustics. This is the number of photons in the photon
map
on page 7894 used for caustics. Increasing this value increases the accuracy
of caustics, but also increases the amount of memory used and the length of
render time. Decreasing this value improves memory usage and render time,
and can be useful for previewing caustic effects. Default=10000.
Average GI Photons per Light Sets the number of photons emitted by each
light for use in global illumination. This is the number of photons in the
photon map used for global illumination. Increasing this value increases the
accuracy of global illumination, but also increases the amount of memory
used and the length of render time. Decreasing this value improves memory
usage and render time, and can be useful for previewing global-illumination
effects. Default=10000.
Decay Specifies how photon energy decays as it moves away from each light
source. This value is given by 1/(distance decay ), where distance is the distance
between the light source and an object, and decay is the value of this setting.
Default=2.0.
The most common values are:
■ 0.0 The energy doesn't decay, and photons can provide indirect
illumination throughout the scene.
■ 1.0 The energy decays at a linear rate, proportionally to its distance from
the light. That is, a photon's energy is 1/distance, where distance is the
distance from the light source.
mental ray Renderer | 6103