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Next: 2.5 Participating Media Up: 2. Physics Shaders Previous: 2.3 Materials

# 2.4 Photon Tracing

Caustics and global illumination are computed by photon tracing. Each object needs a photon material shader for photon tracing. A photon shader will usually have the same name as the corresponding material shader, but with ```_photon`'' appended. When using one of these photon shaders in a material that uses the corresponding material shader (which has the same name but without ```_photon`''), omitting all photon shader parameters causes mental ray to pass the material shader parameters to the photon shader. This avoids having to specify all parameters twice.

Diffuse-glossy-specular Material Photon Shader: dgs_material_photon

The photon shader dgs_material_photon is used for photon tracing of objects that have the dgs_material material shader. It has the same parameters as dgs_material.

Dielectric Material Photon Shader: dielectric_material_photon

The photon shader dielectric_material_photon is used for photon tracing of objects that have the dielectric_material material shader. It has the same parameters as dielectric_material.