Temporal Denoising: EXR image sequence node in the compositor is missing vector output

Question

I'm on Blender 3.5 and trying out temporal denoising within the compositor as shown in this video by statix vfx: https://www.youtube.com/watch?v=851cEK0Taro&t=3s

I've rendered my EXR sequence with the vector pass enabled and motion blur turned off but when I add my EXR image sequence node to the compositor there's only a "combined" and "alpha" output. the "vector" (purple) output is missing.

I can see the individual vector pass in the blender compositor viewer node so I know it's being rendered.

Why is it missing? Do I have to set up the File Output in a specific way to receive this pass in order to access it from an image sequence node later?

Answer 1

When rendering, you need to set your File Output node to OpenEXR MultiLayer. Select the node, and press N to open the sidebar, if it isn't already open, the click the Node tab. Set the fileformat to OpenEXR MultiLayer, then click Add Input to add more input sockets. They will be RGB sockets, but vectors are compatible with RGB, since both basically hold three float values, and OpenEXR can hold values outside the normal RGB range, including negative values.

When importing later, Blender will recognize the files as multilayer, and show enough sockets. Once again, they'll be RGB sockets, but you can safely use the layer holding the vector data as a vector.

As side-note, I have tried, albeit long ago, to use multilayer for texturing, but the shader editor would only recognize the first layer.