CG Compositing Series - 4.1 LightGroup / AOV Paradox

In this final installment of the CG Compositing Series, we focus on using LightGroups and Material AOVs together in a single workflow, and the paradox that come with it.

Why do these 2 rebuild methods seem to clash?

This video explores:

The complications of splitting LightGroups per Material AOV
A method for transferring changes between setups using a Difference Map
The pitfalls of using Subtraction and the advantages of using Division
A comparison of math operations: Add/Subtract vs Multiply/Divide
A stress test of the Division-based setup
Template layout strategies and rules to keep your rebuilds stable
Carrying changes across the template from the 1st rebuild to the passes of the 2nd for the most interactive user experience.

The video wraps with ideas and techniques you can apply in your own CG Templates.

If I could ask one small favor from you, it would be to help share this video, or the blog post, to compositing or VFX friends and colleagues. Whether it's in a group chat, work chat, discord, linkedin post, I believe this knowledge is too important to keep secret. I would love to see this amazing workflow become more commonplace in the world of Compositing. Thank you.

For a full blog post write up, images, and downloads, please visit the post on my CompositingMentor blog:
https://compositingmentor.com/2025/05...

You can find links to the MergeDivide.nk along with the junkyard renders, and demo nuke scripts at the bottom of the blog post.

Timestamps:

00:00:00 - Intro
00:00:53 - What is the LightGroup/AOV Paradox?
00:06:12 - Splitting AOVs per LightGroup
00:09:09 - Problems with Splitting Workflow
00:18:21 - Transfer Changes Workflow
00:20:11 - Subtractive (Absolute) Difference
00:26:06 - Subtractive Difference Problem
00:32:08 - Division (Relative) Difference
00:39:55 - Stress Testing Division Difference
00:43:50 - Workflow Tips
00:45:27 - Posssible Rebuild Layouts
00:47:45 - Carry Changes throughout Template
00:52:10 - Rules and Caveats
00:56:41 - Provided Example Templates
00:57:31 - Template Ideas and Inspiration
01:00:25 - Outro

A huge shout out to Ernest Dios for being one of the true masterminds behind this amazing technique. Also a big thank you to Alexey Kuchinski for all of his mentorship.