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 Mode - allows you to chose the mode in which the color of the light material will be specified.
Light Color - when the Color Mode is set to Color this parameter controls the color of the light material.
Temperature - when the Color Mode is set to Temperature this parameter controls the color of the light material.
Color Multiplier - multiplier for the Light Color
Opacity - a 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 light 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 Camera 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
Direct Illum - when checked all objects that have the particular V-Ray light material applied to them will be considered mesh lights and will emit direct light.
Subdivs - this value controls the number of samples V-Ray takes to compute lighting. Lower values mean more noisy results, but will render faster. Higher values produce smoother results but take more time. Note that the actual number of samples also depends on the DMC Sampler settings.
Light cut-off threshold - this parameter specifies a threshold for the light intensity, below which the light will not be computed. This can be useful in scenes with many lights, where you want to limit the effect of the lights to some distance around them. Larger values cut away more from the light; lower values make the light range larger. If you specify 0.0, the light will be calculated for all surfaces.