This page gives information on the VRayLightMix render element.

If changes to the render element are made while the VFB is open, those changes are reflected after the VFB is closed and reopened.


Overview

The Light Mix render element provides adjustment control to the lights in the scene from inside the V-Ray Frame Buffer (VFB2). When a Light Mix 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 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 in the scene with a single click. This feature can handle individual lights as easily as light groups or custom selections.

Read more about LightMix on the Chaos blog and the V-Ray 5 for Maya Courseware dedicated page.






To use render elements, select from the Available render elements column and click the Add button to add the passes you wish to generate at render time. When you render the scene, the added render elements listed in the column on the right, will also render, which can be viewed from the VFB window's channel drop-down menu.

For more information on the parameters on this dialog, see the Render Elements tab page.


 

Parameters

Enabled – When enabled, the render element appears in VFB2.

Denoise – Specifies whether to denoise the Light Mix render element, if a Denoiser render element is present. Note that if the Group by option is set to Manual light selects, this option overrides the Denoise parameter of each Light Select.

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;
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.

Each grouping mode automatically creates Environment and Self Illumination render elements and Light Mixing adds them as groups. The information from the light emitting materials is stored in the Self Illumination channel, while the Environment info is stored in the Environment channel.

Separate emissive materials – 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 Maya native Standard Surface material with non-black emission color.

Save "Rest" Channel – Disabled by default. When enabled, saves a separate Rest channel in the rendered files. The Rest channel includes all the lights, which have not gone to any Light Selects. For example, if a scene has more than 64 lights which are not grouped in any way, the first 64 lights will have individual Light Selects and the rest will go the Rest channel.



How to Set up

To set the LightMix for use:

  1. Add the LightMix Render Element to your scene. UI: ||Render Settings|| > Render Elements tab > Add LightMix
    1. Then, render the scene.
    2. In the new VFB > Layers, set the Source to LightMix.
    3. Now you can tweak your lights!

  2. Add the LightMix Render Element directly from the VFB.
    1. In the VFB > Layers, set the Source to LightMix.
    2. Click on Add LightMix to the scene.
    3. Start a new render to apply the changes. Now you can tweak your lights!

Before rendering, set your lights to white (neutral) color and boost their intensity.

Rendering with lower intensity and then increasing it from the LightMix might produce noise in your render. If this happens, use the "To Scene" option and re-render the scene.


LightMix Mode Parameters

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 lights.

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.



LightMix Selection


Right-clicking on an item in the LigtMix list allows you to select that item in the viewport.


Select lights in the scene – Selects the current item in the viewport.
Add lights to the selection – Adds the current item to the selection in the viewport.
Remove lights from the selection – Removes the current item from the selection in the viewport.


When the lights are grouped in any way, depending on the setting of the Group by parameter, selecting a group, selects all the lights included in it.


There are some general groups that are automatically created by the Light Mix RE, which allow you to control groups of lights:

All – Turns on/off all lights.

Environment – Contains the emitting effect of any map placed in Maya's Environment overrides (Render Setup > Overrides 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).


Common Use

The LightMix allows changing the appearance of the image by controlling the lights in the scene even after the rendering is done.

In the example below, we've created two different light setups with the help of VRayLightMix: daylight and dusk. The Daylight appearance is achieved by using sunlight and an additional softlight to simulate light coming from the outside. The Dusk appearance is achieved by setting the sun Multiplier to 0, changing the color multiplier of the outside light to blue, increasing the intensity multiplier of all interior lights and tinting them with warmer colors (all ceiling and built-in furniture VRayLights), adjusting the self-illumination multiplier of desk and ceiling lights, shaded with VRayLightMtl.