Light Mix

The Light Mix render channel provides adjustment control to the lights in the scene from inside the V-Ray Frame Buffer. When a Light Mix render channel 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 to re-render your final output or navigate to individual light parameters during IPR. Furthermore, modifications made in the Light Mix 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.

In the example, you can see how the lights are mixed so that in one instance, it is dusk, with a nice sunset, and in another instance, it is nighttime. These effects were achieved solely by adjusting the lighting.

Read more about LightMix on the Chaos blog.

1. Add the Light Mix render channel to your scene from the View Layer Properties > Render Channels > Light Mix. 

2. Open the V-Ray Frame Buffer and start a new render. This will automatically change the Source to Light Mix.

3. Open the Source layer, and in its Properties, you can start adjusting your lights.

See the Render Channels page to find out where you can find these properties.

Create Rest Channel – Creates a Rest channel along with the other light groups. The Rest channel 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).

Denoise – Enables the render channel's denoising, provided the Denoiser is enabled.

Tag Lightmix –When enabled, adds a flag to the light mix channel. All light selects part of the Light Mix must have light_select_in_lightmix=true. With this flag set to true it is possible to have LightSelects outside
of the LightMix.

In the V-Ray Frame Buffer, 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. Light Mix automatically creates Environment and Self Illumination render elements.

Reset – Resets all changes made to default values.

Save – Saves the changes as a 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.

There are some special categories 

All – Turns on/off all lights.

Environment – Contains the emitting effect of any map placed in the V-Ray Environment node.

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). This channel is created when Create Rest Channel is enabled in the Light Mix node properties.