2009
■ 2.0 (inverse square) The energy decays at an inverse square rate. That is,
a photon's energy is the inverse of the square of the distance (r) from the
light source (1/r2).
In the real world, light decays at the inverse square rate, but this gives strictly
realistic results only if you provide a realistic value for the energy of the light.
You can use other values to help adjust indirect illumination without worrying
about physical accuracy.
Caustic Photons Sets the number of photons emitted by the light for use in
caustics. This is the number of photons in the
photon map on page 8090 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.
GI Photons Sets the number of photons emitted by the 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.
mental ray Light Shader Rollout
Select a light. > Modify panel > mental ray Light Shader rollout
Note: This rollout appears only if you have enabled the mental ray extensions
by using the mental ray Preferences panel.
NOTE This rollout does not appear on the Create panel; only on the Modify panel.
The mental ray Light Shader rollout lets you add
mental ray shaders on page
5974 to lights. When you render with the
mental ray renderer on page 6230, light
shaders can alter or adjust the light's effect.
To adjust the settings for a light shader, drag the shader's button to an unused
Material Editor sample slot. If the software prompts you to choose Instance
or Copy, be sure to choose Instance. (If you edit a copy of the shader, you will
have to drag the sample slot back to the shader button on the Light Shader
rollout before any changes take effect.)
Common Lighting Rollouts and Dialogs | 5115