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05 Unreal compositing

Status: Established. Exact panel names vary between Unreal Engine 5 versions; check against your version.

The goal is that the performer looks lit by, and standing in, the virtual world.

Getting the plate into Unreal

Method Good for
Media Plate actor (UE 5.1+) The simplest way to show a video or image sequence in the level
Composure plugin Layered comps: plate, CG, mattes and colour passes, with a live preview
Card in the world A textured plane placed in 3D, useful for 2.5D shots and depth effects

Use an image sequence with alpha (PNG or EXR) for final renders; video files can drift a frame in Movie Render Queue.

Make it sit in the world

  1. Match the lens. The tracked camera's focal length and filmback come from the solve (doc 04).
  2. Match the light. Point the main virtual light the way the real key light came from; use the grey ball from set as reference.
  3. Grade the plate toward the world. Black level, white balance and saturation first; a little of the set's ambient colour on the performer's edges.
  4. Contact shadows. A performer with no shadow floats. Options: a shadow from a proxy shape (capsule or rough mesh following the performer), or a shadow pass composited over the plate. In recent UE 5 versions, holdout and alpha output in Movie Render Queue help separate passes.
  5. Rim and spill from the world. If the set has a bright sign behind the performer, add a matching edge light in the comp.
  6. Depth. Put foreground CG in front of the performer (smoke, debris, a pillar edge) so they are inside the space, not on top of it.

Rendering

  • Render with Movie Render Queue: fixed frame rate matching the plate, anti-aliasing samples raised for motion.
  • Render CG and plate separately when you plan to finish in After Effects or DaVinci Resolve. Render the final comp in Unreal when it's a fast turnaround.
  • Keep one test-cube render per shot in the project folder as proof of the track.

Using an AI agent with Unreal

If you run an Unreal MCP server (several open-source projects exist), the agent can place the media plate, import the camera CSV and queue renders. Keep these rules:

  • One script builds the set and can be re-run: the agent edits the script, not the level by hand.
  • Tag everything the agent creates so it can be found and rebuilt.
  • The agent shows a screenshot at each checkpoint; a person approves before render.