VRay for 3ds Max Manual

VRayLightMtl Parameters

	General
	Parameters
	Notes

Search Keywords: light material, self-illumination

General

The VRayLightMtl is a special material provided with the V-Ray renderer. This material is generally used for producing self-illuminated surfaces. It also allows faster rendering rather than with a Standard 3ds Max material with self-illumination enabled. It also allows to turn an object into an actual mesh light source.

Parameters

Color - this is the self-illumination color of the material.

Multiplier - this is the multiplier for the Color. Note that this does not affect the texture map, if specified.

Texture - a texture map to use for the self-illumination 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.

Direct illumination

The controls in this section allow you to turn the objects which have this VRayLightMtl material applied into actual direct mesh light sources. The effect is equivalent to creating a VRayLight in Mesh mode for the same object. The controls in this section are intentionally simple; if you need more control over the light source (exclude objects from illumination etc), it is better to use a VRayLight instead.

There are currently some restrictions on using these options. For more details, please see the Notes section below.

On - when enabled, turns any objects with the same material into mesh light sources. Note that this currently does not work if the material is inside a Multi/Sub-object material.

Subdivs - controls the number of samples used for direct sampling of the mesh light. Lower values may be faster to calculate, but may introduce noise in the image. Higher values reduce the noise, but increase render times.

Notes

• You can use the VRayLightMtl as a light source assigned to an object. Increasing the multiplier will affect the GI solution and will produce more light. Note that overbright colors may look the same as pure white but the GI results will be different. For more information see the Examples section.
   
• If you know the photometric power of a self-illuminated object in lumens (e.g. 1700 lm for a 100-watt bulb) you can calculate the multiplier for VRayLightMtl if you divide the lumens by the surface area of the object in meters (the 3ds Max Measure utility can be used for this), provided that the self-illuminated color is pure white.
   
• The direct illumination options currently only work properly if the VRayLightMtl material is the only material applied on the object. They will not work if the material is part of a complex material like a Multi/sub-object material or a VRayBlendMtl material. This restriction will probably be removed in a future release.
   
• The direct illumination options do not work properly if the object with the VRayLightMtl has motion blur. This will be corrected in a future release.