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.
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.
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.
Copyright (©) 1986-2009 by mental images GmbH