Compositing COPS Info Dump

General

• COPs was fully revamped in Houdini 21 (2025)
• Added GPU processing and has VEX integration
• Global preferences and defaults: affect all compositing in Houdini
• Project settings: affect a specific .hip file

Nodes

• Channel Copy to get the other passes
• Generator (has image tab) and filter nodes.
• in compositing, use the direct reflection pass then use subtract.
• expand, dilate erode node
• Composite (Uber Node. )
  • Like you can perform add, subtract etc
• Dilate/Erode only on the Alpha Channel. After this you need a premult node.
• Edge Blur Node before the Premult Node.
• Fog Node
• Use Render through File ROP Output
• The Sidefx Labs Maps Baker tool (maps-baker): bakes UVs, normals, positions, and other attributes by querying SOPs; works with COPs via vex lookups
• You can drag a COP node onto a texture path and prefix with 'op:' to connect to SOP data
• Denoise node can be used inside COPS
• Channel Copy on separate R, G, B then do Radial Blur
  • Do simulate the chromatic abberation
• Mask input on the node expects an alpha. But you can specify to search for color channel is alpha is not available. It's not like having black and white mask in a jpg file.
• Render through File ROP Output

Cops lets you query info from sops via vex. The Sidefx Labs Maps Baker tool uses this by looking up uv's and querying sops normals, positions, other attributes, and bake them down into images in cops.

You can use cops directly with sops by just drag-n-dropping the cops node onto a texture path, and then prefix it with 'op:'.

F, P to frame data.