Compositing Overview

Table of Contents:

<Insert Table of Contents Here>

See screenshots at the very end of this document for a visual depiction of the entire workflow as described

Working in Linear

Compositing and keying in Fusion should be done in linear color space, meaning you are working with the actual information captured by the camera rather than how the footage appears (which is determined by a gamma curve that translates what the camera sees into color spaces like log or Rec709).

Before doing any work in Fusion you should convert your footage to linear – in other words remove the gamma curve.

Converting to Linear

Use a Gamut node to convert sRGB or Rec709 Footage to Linear

• Source Space: Set to “sRGB,” leave “Remove Gamma” checked 
• Output Space: Leave as “No Change”

Use a CineonLog node to convert Log or CameraRaw Footage to Linear

• Mode: Set to “Log to Lin”
• Log Type: Select the corresponding log format to your camera footage, for ex. “ARRI LogC” for Arri Alexa Footage

EXR – EXR material should already be linear and should not need a conversion. In special cases (such as an EXR rendered in ACEScg color space), use the Gamut tool and select the relevant Source Space.

Outputting/Previewing from Linear

You can have nodes in place at the end of your node flow to “de-linearize” the composite back to the footage’s original color space. This is useful for viewing the material in Rec.709 as you are working or outputting to Resolve’s color tab in log for grading.

You can set this conversion early on in the workflow, and just make sure to do your compositing work between the linearizing and de-linearizing nodes.

To de-linearize, set a node of the same tool used to convert your footage to linear, but with the settings “flipped.”

Gamut for sRGB or Rec709

• Source Space: Set to “No Change”
• Output Space: Set to “sRGB”

CineonLog for Log or CameraRaw

• Mode: Set to “Lin to Log”
• Log Type: Select the corresponding log format to your camera footage, for ex. “ARRI LogC” for Arri Alexa Footage
  

If you are working with log or Raw footage that is now de-linearized back to log, you can either:

• Output to Resolve’s color tab to grade in log
• Convert from log to Rec709 with a Color Space Transform node:
  • Input Color Space: Select based on your camera/footage
  • Input Gamma: Select based on your camera/footage
  • Output Color Space: Rec709
  • Output Gamma: Rec709

Working In ACES

An alternative to working in Linear Color is working in ACES, a system that unifies footage from different camera sources to a single color space that also responds to color adjustments in a way that is more similar to film.

Compositing with CGI in ACES is an option when the CGI was created in Cinema4d’s ACEScg color space.

Converting footage to ACEScc

Opt1. Using OCIO Colorspace

• Download the config files for OCIO
• Add the OCIO Colorspace Node. The settings should be:
  • OCIO Config: Browse to where you saved your config file
  • Sour Space: Select based on your camera
  • Output Space: ACEScc

Opt.2 Using ACES Transform OFX

• Add the ACESTransform node, the settings should be:
  • ACES Version: Set to latest
  • Input Transform: Select based on camera
  • Output Transform: ACEScc

Converting CGI EXR to ACES

Opt1. Using OCIO Colorspace

• Download the config files for OCIO
• Add the OCIO Colorspace Node. The settings should be:
  • OCIO Config: Browse to where you saved your config file
  • Sour Space: ACEScg
  • Output Space: ACEScc

Opt2. Using ACES Transform OFX

• Add the ACESTransform node, the settings should be:
  • ACES Version: Set to latest
  • Input Transform: ACEScg
  • Output Transform: ACEScc

Outputting/Previewing From ACES

As described in the Outputting/Previewing From Linear section, you can have nodes in place at the end of your node flow to convert out of ACES.

The options are:

• Convert to Rec.709 with another OCIOColorspace
  • Source Space: ACEScc
  • Output Space: Rec.709
• Or ACESTransform node:
  • Input Transform: ACEScc
  • Output Transform: Rec.709
• No conversion in Fusion – output to the Color tab in ACES

Keying Greenscreen

Delta Keyer

The Delta Keyer will offer the most control in Fusion for Davinci Resolve. It is best used by combining a Delta Keyer node with a Clean Plate node.

Create a Delta Keyer node and a Clean Plate node. Your greenscreen footage (after it has been converted to linear) will connect to both nodes. The Clean Plate node will connect to the Clean Plate input (pink arrow)

Clean Plate Node – This tool is used to smooth out lighting differences on the greenscreen, and it also performs the functions of the Pre-Matte tab of the Delta Keyer, so you will not have to adjust those settings within Delta Keyer.

• Plate tab
  • Method: set to “Ranges.” Draw selection boxes around the green screen until all of it is selected.
  • Erode: Dial this up slightly so that the greenscreen isn’t eating into the foreground/subject
  • Grow Edges: Dial this up all the way to fill the entire frame with shades of green. Check Fill if Grow did not fill the frame completely.

Delta Keyer Node – Connect the Clean Plate to the Delta Keyer Node via the Clean Plate Input (pink arrow). A Decent key should appear as soon as it’s connected.

• View Mode: Most useful options are Final Result and Status. When in Status: anything that is black is completely transparent, anything that’s white is completely opaque, any gray is semi transparent.
• Matte tab – This is where you need to make most of your adjustments.
  • Threshold Low – Dialing up reduces the amount of gray in the mostly black areas (status view), basically cleaning up the background
  • Threshold High – Dialing up reduces the amount of gray in mostly white areas (status view), basically cleaning up the foreground/subject.
  • Clean Foreground & Clean Background – Avoid pushing the Threshold controls too far by using them in conjunction with Clean Foreground & Background.
  • Erode/Dilate – Grows or shrinks the matte
  • Blur – Blurs edges of the matte
    

Ultra Keyer

The Ultra Keyer is a relatively simple keying too and does not have as many controls as the below Delta Keyer option.

• Pre Matte Tab
  • Background Color – click or draw selection boxes on the greenscreen. Note: this should be done on a viewer window showing the footage from a node preceding the Ultra Keyer node. This is because the Ultra Keyer is applying the matte as soon as it’s applied
• Matte Tab – Clean up and refine key. It can be helpful to set the viewer to alpha mode (select the viewer and hit “a” on the keyboard) while adjusting these settings
  • This tab contains many of the tools in the Delta Keyer Matte tab. See that section for details.

Set Keyed Footage as Matte

Using the Delta Keyer results in a very noisy image. The solution is to use the keyed footage as a matte for the original footage, rather than the end result.

Create a Merge node

• The Original Footage (un-keyed) goes into the Background Input of the Merge (green arrow)
• The Keyer node goes into the Effect Mask Input of the Merge (blue arrow)
• The footage you are using as the background to replace the green screen will go into the Background Input (gold arrow)

Add a Matte Control node between the Original Footage and Merge to remove green spill (green reflected onto the foreground) and fringe (semi transparent pixels, often on the edge of foreground)

Spill and Fringe are things that you can address in the tools within Keyer nodes. However these adjustments will be lost once setting the key as a matte, therefore they should be addressed with the Matte Control.

• Original footage goes into the Background Input of the Matte Control
• Keyer goes into the Foreground Input

Matte Control Settings

• Matte Tab:
  • Combine: Set to “Combine Alpha”
  • Blur, Contract/Expand affect the fringe in a self explanatory way
  • Gamma affects the transparency of the fringe
• Spill Tab:
  • Spill Color: set to “Green”
  • Spill Method: “Well Done” is considered good for green screen
  • Dial up the Spill Suppression
  • Dial up or down the Fringe Gamma and Fringe Size controls to your desired effect

Compositing Keyed+Matted Footage with CGI

A Merge tool is used to combine different elements in Fusion, such as a greenscreen live action foreground with a cgi background. Here are the basics of the Merge tool:

• Foreground Input (green arrow): Connect to the element you want to appear in front or on top 
• Background Input (gold arrow): Connect to the element you want to appear behind or below
• Effect Mask Input (blue arrow): Connect to the element you want to use as a mask/matte for your Foreground Input.
• Under Merge Settings
  • Size: Changes size of the foreground footage (Rescaling the background requires a transform node preceding the Merge)
  • Apply Mode: Blending modes

Example screenshots of The Workflow

Linear workflow

ACES workflow