Light Group AOVs

Table Of Contents

• Introduction
• Creating Light Groups
• Setting Up Light Group AOVs
• Light Group AOV Options
• Light Groups in Detail

Introduction

For even more control in post you can make use of Light Group AOVs. The light group functionality allows you to output per-light AOVs for most of Redshift's Integrated beauty AOVs. With separate passes for each light you can do things like increase or decrease the exposure of individual lights and change their color temperatures without having to re-render. Light groups can contain a single light or multiple lights for added flexibility and organization, allowing you to group together lights that fill similar roles.

Before you can start outputting light group AOVs first you have to create light groups and assign your lights to them. For more information please see here.

Compatible Light Group AOVs

• Beauty
• Diffuse Lighting
• Reflection
• Specular Lighting
• Refraction
• GI
• SSS
• Emission

Incompatible Light Group AOVs

• All RAW AOVs
• Utility AOVs
• Caustics
• Custom
• Puzzle Mattes
• Shadows

Creating Light Groups

Setting Up Light Group AOVs

Light Group AOV Options

Global AOV

Select the Global AOV mode for Light Group AOVs. In most cases the Remainder mode is preferable. 

• All - This mode outputs an AOV with the combined result of all the Light Groups in the scene, just like a normal version of the AOV without any Light Group separation.
• Remainder - This mode outputs an AOV with any remaining information not covered by the light groups selected.from the Light Group list. This AOV contains light groups and lights that are not selected as well as any point-based effects that are incompatible with light groups. This remainder AOV will be output with the suffix "other."

All Light Groups

When toggled on this lets you quickly output a Light Group AOV for every Light Group in your scene without having to manually specify each one in the Light Group List.

Light Group List

This is where you select or list the light groups that you want to output for this AOV.

Light Groups in Detail

Example scene

There are 4 total lights set up in the following Light Groups:

• Light Group: key_light
  • A single key area light with volume contribution.
• Light Group: disc_spot_lights
  • A disc shaped area light with volume contribution.
  • A caustic casting spot light with no volume contribution.
• Light Group: dome_light
  
  • One Redshift dome light with volume contribution.

Below are the resulting Light Group AOVs for their respective shading elements using both ray-traced effects and point-based effects for comparison when applicable. For the ray-traced examples everything is rendered with ray-traced effects (brute force GI, ray-traced SSS) with the exception of photon caustics. For the point-based examples the GI is rendered with Iraddiance Cache and Irradiance Point Cloud and the SSS is point-based and still contains the photon caustics. 

Beauty

Note that in the point-based example all non-ray-traced effects show up exclusively in the Other or All AOVs. So you have no way of separating the global illumination, sub-surface scattering and caustic contribution on a per-light basis, instead they are all lumped together.

For the ray-traced example only the photon caustics show up in the "other" AOV here even though they are being cast by the spot light. Since caustics are not ray-traced they cannot be output with their appropriate light group and thus end up in the Other or All passes.

Diffuse Lighting

Global Illumination

Reflection

Note that in this case the light seen in the Other AOV is the photon caustics seen in the reflections.

Specular Lighting

Refraction

Note that in this case the light seen in the Other AOV are the photon caustics seen through the refractions.

Sub Surface Scattering

Volume Lighting

Emission

Note that if a light is visible in your scene it is output in the Emission AOVs as demonstrated above.

Light Groups in Practice

Compositing Light Group AOVs

Light Group AOVs can be composited easily just like any other non-raw AOV, by adding the result together in your preferred compositing package. For some examples on AOV compositing please see here.