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Set up mental ray for Maya raytracing

Render with global illumination and caustics

Flag objects to cast and receive photons

 

User Guide > Rendering and Render Setup > Lighting > mental ray for Maya Lighting > Render with global illumination and caustics > 

Turn on photon emission for a light source

At least one direct light source (a point light or spot light) must emit photons for global illumination or caustics to work.

For more information on direct light sources, see Sources of direct light.

To turn photon tracing

1. Select the light source you want to emit photons.

   For example, spot light.

2. Open the Attribute Editor ( +a).
3. Select the light’s shape tab.
4. Set Decay Rate to Quadratic.

   This causes light levels in the scene to decrease in intensity based on the inverse square law (naturally).

5. Set the photon emission attributes.

   See mental ray attributes for lights (point, spot, directional, area).

6. Repeat this procedure for every light source you want to emit photons.