Advanced Compositing in Assimilate Live FX!

Most people know that you use ASSIMILATE Live FX for various Virtual Production workflows and also for live compositing, but did you know you can also use it as a powerful and screaming fast offline compositing software?!

Here is the full tutorial:

Overview

In this tutorial, I’ll go over some advanced compositing techniques for Assimilate Live FX, which also apply to Scratch.?

Here are some important things to know about compositing in Live FX:

Because Live FX is a layer based compositor (instead of a node-based compositor), using multiple single-pass exrs are better than using multi-layered exrs.?

Assimilate is the fastest compositor I’ve ever used. I have used Davinci Fusion Standalone, After Effects, I've even dabbled in Nuke briefly, but they are very slow compared to Assimilate.

Even with these 12k exr sequences, you can see I am layering 10 different exrs and still able to preview changes very quickly.?

It does take some getting used to, and it lacks a lot of advanced tools that you would find in other compositing software, but even if I need to use those tools, I only use them for the specific parts that I need.

For example, Assimilate cannot use Cryptomattes in any meaningful way. So I might use Fusion or Blender to take the crypto matte and render out mattes of the objects or materials I need mattes for, and then bring those mattes into Assimilate to finish.?

Even with that round trip, I can work faster and more efficiently using this pipeline.

Opacity and Blend Modes

To change how much opacity a layer has, go to the fill tab on the top-left menu, and on the left, you can change the opacity from 100 (default) to something less to blend the images together.

You can use any of the common blend styles as needed for your project. In this case I have the lighting pass of the Sunlight, and I'm able to subtract that from my scene, effectively re-lighting my scene after the initial render in compositing.

Working with the Alpha Channel

The main tab that you should think of when you are using a file with an alpha channel, is the Fill/Matte tab on the bottom left.

It may also help to start your project with a Filler, such as Black.

After you've created a Filler layer and entered your project, you can now add your foreground elements, in this case, I'm adding a Noisy and De-Noised beauty pass. These both have alpha channels and by default, they are enabled, so the sky looks black.

Now I drop in my environment pass on the top of the layer stack, so that it goes behind the other two files.

Some times you may have an alpha channel off by default and you want to turn it on, such as this exr:

In the Fill/Matte menu, enable the alpha menu, and now the alpha channel will be active.

Re-Map EXR Channels

To re-map the layers of EXR files, select the layer you want to change and in the top left of the main menu, select the "Node" menu.

Select the channel selection, then re-map R,G,B and A to the correct channels.

Before we re-map, in this case the channels came into Assimilate incorrect.

After we re-map the values correctly, the image looks correct.

Some EXRs and some Render Passes from various 3d programs will have other passes, that do not correspond with R,G,B and A. For these you may need to experiment to get the desired results.

In this example, this is the Z-Depth Pass, and instead of R,G,B,A, we need to re-map R,G,B,A to Y,Y,Y,A

Working with Mattes

You can use black and white mattes in various ways in Assimilate.

Let's say we want to bring in a Z-Depth Matte, to control the Depth Of Field of our scene.

• Make sure your Z-Depth Layer channels are Mapped correctly.
• Create a New Layer.
• Fetch or import your matte.
• Go to the Fill/Matte Menu
• Drop the matte in the "Drop Layer Matte" field.

• Change the layers to NOT use the Alpha channel. This is incorrect:

This is correct:

Now that the matte is set up, any adjustments that we make to this layer will use the Matte to influence the effect.

Outro and Tags

There's a quite a bit more to add, but that's going to wrap up this article, hope you enjoyed and make sure to subscribe!

Compositing Software: ASSIMILATE Live FX

Computers: Silverdraft

Render Engine: OTOY 's Octane Render

Cloud Rendering: Render Network Foundation

Lead 3d Artist: Mike Hodgetts

Jeff Edson , Matthias Aderhold , Alexander MacLean

Hardie Tankersley , Amy Gile