V-Ray Light Material parameters
Search Keywords: light material, self-illumination
The VRayLightMtl is a special material provided with the V-Ray renderer. This material is generally used for producing self-illuminated surfaces.
Color - this parameter controls the color of the light material. .
Color multiplier - a multiplier for the Color
Transparency - a color or texture to use as opacity for the material. Note that making the material less opaque does not affect the intensity of the self-illumination color. This is so that you can create perfectly transparent materials that nevertheless still emit light.
Emit on back side - checking this option makes the object emit light from its back side as well. If this is off, the material is rendered as black on the back sides.
Compensate Exposure - this option is used when rendering with the V-Ray Physical Camera. When enabled the intensity of the material will be adjusted to compensate for the camera exposure
The Material ID group is described here