VRayLightMix

The VRayLightMix render element provides adjustment control to the lights in the scene from inside the V-Ray Frame Buffer (VFB2). When a VRayLightMix render element has been added before rendering, the intensity and color of the lights and light emitting materials can be changed directly from the VFB during and after rendering; lights and self-illuminating materials can be enabled or disabled on the go, without the need of re-rendering your final output, or navigating to individual lights parameters during IPR. Furthermore, modifications made in the LightMix can be transferred back to the actual lights and materials in the scene with a single click. This feature can handle individual lights and emitting materials as easily as light groups, layers or custom selections.

Find out more about how VRayLightMix works here: Chaos Blog. 

VRayVFB – When enabled, the render element appears in VFB.

Denoise – Specifies whether to denoise the Light Mix render element if a VRayDenoiser render element is present.

Group by – Specifies how to group the lightning information:

Instanced lights – If there are instanced lights in the scene, each group has its separate channel. All unique lights in the scene are stored in their individual render channels;
Individual lights – Lighting information of each light is stored in a separate channel;
Grouped lights – Lighting information of each group of lights is placed in a separate channel. All lights that are not attached to any group in the scene are stored in their individual render channels;
Layers – Lighting information for each layer is stored in a separate channel;
Manual light selects – Render channels are created based on the existing Light Select render elements in the scene. Lights that are not specified there, are collected in single render channel called Rest.

Separate emissive material – When enabled, illuminating materials are also included in the VFB LightMix controls together with scene lights. The materials which V-Ray respects are: VRayMtl with non-black self-illumination, VRayLightMtl, and 3ds Max native Physical Material with non-black emission color.

Include "Rest" channel when saving to file – Disabled by default. If enabled, it creates an additional channel when exporting, which stores all the lights not included in any Light Selects or exceeding 62 individual lights. For example, if a scene has more than 62 lights which are not grouped in any way, the first 62 lights will have individual Light Selects and the rest will go to the Rest channel.

When the Source is set to LightMix, you can enable/disable lights and adjust light intensity and color during and after the render. The modifications can be saved as light mix presets and reused. VRayLightMix automatically creates Environment and Self Illumination render elements.

Reset – Resets all changes made to default values.

Save – Saves the changes as light mix preset.

Load – Loads a light mix preset.

To Scene – Applies the current VRayLightMix changes to the scene. This sends all changes to colors/intensities back to the scene items (except the items which were left out in Rest). This option is only available when the render has stopped.

To Composite – Sends the Light Selects from LightMix to Composite for additional post adjustments.

Recent – Shows a list of recent light mix presets.

Checkbox – Enables/Disables the selected light.

Multiplier – Specifies an intensity multiplier.

Color Slot – Specifies a color for the selected light.

All – Turns on/off all lights.

Environment – Contains the emitting effect of any map placed in 3ds Max's Environment map slot (Rendering > Environment) or the Environment overrides (Render Setup > V-Ray tab > Environment rollout).

Self Illumination – Contains either all parts of the scene which have a self illumination material, or only the parts of the scene which haven't been included in any groups specified by Light Selects. Some parts of the scene might also be present in this category if the individual number of self emitting materials exceeds the maximum range of 62 for all the Light Selects.

Rest – Includes all the individual lights that are not part of any group defined by a Light Select or exceeding the limit of the list (the limit of the list is 62 individual lights or Light Selects).

A context menu is available when you right-click on a light's name/label in the LightMix properties. The same menu is also available when you right-click on a listed material. The menu also respects the LightMix grouping modes and can be used with instancing, groups, or layers.

When you right-click on a light:

Select lights in scene – Selects the lights.

Add lights to the selection – Adds the lights to the current selection.

Remove lights from selection – Removes the lights from the current selection.

When you right-click on a material:

Select lights in scene – Shows the material in an additional Slate Material Editor view named VRayPickMtlView and loads the parameters of the material.

Add lights to the selection – Adds the material in the current active Slate Material Editor view (if not already there) and loads the parameters of the material.