Skip to content

Compositor

Attaches a Blender compositor node tree to the assembled render scene. Connect to the Scene node's Compositor input.

Properties

Node Tree — select an existing compositor node group from your file. The node tree is attached to the assembled scene and used during rendering.

Tips

  • Compositor node trees used with Scene Assembler should be set up as node groups (not the scene's main compositor directly). This lets you reuse the same tree across multiple Scene nodes or keep it versioned independently of any scene.
  • If no Compositor node is connected, the assembled scene uses whatever compositor is already attached to the base scene (if any).

Limitation: your own compositor tree should have only one Render Layers node

This limitation is about the compositor tree you build and connect here — it's separate from Scene Assembler's own native multi-view-layer merge (see the Scene node and View Layer node pages), which already handles rendering several view layers together in one job internally, with its own generated compositor wiring — Cryptomatte, AOVs, light groups, and your connected Compositor tree all continue to work per layer in that case.

What's still not supported is a user-authored compositor tree that itself references more than one scene or view layer via its own Render Layers nodes.

In stock Blender, a Render Layers node can point at any scene/view layer in the file, and Blender will render that scene/view layer alongside the current one to feed the compositor — this is how multi-scene or multi-layer composites normally work. Scene Assembler doesn't support this in a tree you connect to the Compositor input: every job (merged or not) forces every Render Layers (and Cryptomatte) node in your tree to reference the assembled scene/layer it belongs to. A Render Layers node in your own tree meant to read a different scene or view layer than the one Scene Assembler assembled will not trigger that other render — it gets redirected to the assembled one instead and produces wrong or empty output.

If your tree has more than one Render Layers node, Scene Assembler shows a warning in the N-panel. Supporting a user tree that references multiple independent scenes/layers together may come in a future version, but currently there's no way to do that from your own compositor graph.

Multi-Layer EXR disables compositing entirely

If the output format is Multi-Layer EXR (on Output Defaults or a Scene node's own override), compositing is turned off completely and Blender's native multilayer writer packs every pass — including Cryptomatte — directly into the EXR, keyed by view layer name. Any Compositor node connected here is ignored in that case; Scene Assembler shows a warning when this happens so it's never a silent surprise.