This page gives information on the Light Select Render Element.
UI Path: ||Render Setup window|| > Render Elements tab > Add button > VRayLightSelect
This render element is enabled through the Render Elements tab of the Render Setup window in 3ds Max and displays its parameters in a rollout at the bottom of the window:
Lights – A list of lights included in the VRayLightSelect Render Element.
Add – Adds a light to the VRayLightSelect Render Element.
Remove – Removes a light from the VRayLightSelect Render Element.
Type – Specifies how the list of lights works from the following:
Include – Includes the listed lights in the render channel.
Exclude – Excludes the listed lights in the render channel.
VrayVFB – When enabled, the render element appears in the V-Ray Virtual Frame Buffer.
deep output – Specifies whether to include this render element in deep images.
Color mapping – Applies the color mapping options specified in the Color mapping rollout of the V-Ray tab in the Render Setup window to this render element. This option is enabled by default.
Multiplier – Sets the overall intensity of the render element, where 1.0 is the standard multiplier.
Mode – Sets what type of lighting contribution is generated in the element as follows:
Direct illumination – Lighting within the VRayLightSelect element behaves as normal and contains diffuse and specular information.
Direct raw – Lighting within the VRayLightSelect element behaves as a raw render element.
Direct diffuse – Lights within the VRayLightSelect element output only their diffuse contribution and contain no specular information.
Direct specular – Lights within the VRayLightSelect element output only their specular contribution and contain no diffuse information.
Full – Lights within the VRayLightSelect element provide full output for all information available in the scene such as GI, SSS, reflection, refraction, etc.
Below is an example of how to use the Light Select Render Element in a composite.
For this example, each light is assigned two VRayLightSelect render elements: The first element's mode is set to Direct diffuse, and the second element's mode is set to Direct specular. This gives a finer degree of control to allow separate tuning of each light's diffuse and specular contributions. In addition, two of the lights were rendered with a third element with the mode set to Full.
The images below use 4 lights. These are two Plane lights with a Light Softbox Map (lights #1 and #2), a softbox Plane light with no specular contribution (light #3), and a Dome light.
For Light #3, although the diffuse contribution is low, it is essential to the overall lighting of the scene in this example. This light has no specular contribution, so the Light Select specular element would render as black.
The following diagram shows the compositing formula to recreate all the scene Lighting from light sources when each light in the scene is accounted for in exactly one VRayLightSelect render element in Diffuse mode.
The diagram above illustrates that the sum of all VRayLightSelect Render Element set to Direct diffuse mode represents the VRayLighting render element which can be used in the Back to Beauty composite. For the above equation to work correctly, all enabled lights need to be accounted for exactly once in the VRayLightSelect render elements. This happens by either specifying each light in a separate element, or combining them in a practical manner in several elements and avoiding repetitions.
When the VRayLightSelect render element is set to Direct diffuse mode, the sum of all lights' output composes the VRayLighting render element. It must be noted that VRayAlSurfaceMtl with sss_mix value other than the default 0, doesn't fit this equation.
When the VRayLightSelect render element is set to Direct raw mode, the sum of all lights' output composes the VRayRawLighting render element. This is only true when GI is disabled and there are no dome lights in use.
When the VRayLightSelect render element is set to Direct specular mode, the sum of all lights' output composes the VRaySpecular render element.
When the VRayLightSelect render element is set to Direct illumination mode, the sum of all lights' output replaces the sum of VRayLighting and VRaySpecular render elements in the Back to Beauty composite.
When the VRayLightSelect render element is set to Full mode, the sum of all lights' output composes the Beauty pass. This is only true when the environment is black and no environment override is used. There should be no self-illuminating materials, because they can't be added as contributing light sources in the VRayLightSelect render element. Caustics are not included in the calculation of VRayLightSelect Render Element.