Volumetric Fog Render Pass Possbie?

Hello, I have a question while working on it.I want to print the volumetric dog as a render pass like the picture, but I’m not sure how to do it. Can anyone help me with this?

If you’re using the path-tracer there’s a way to do it by telling it to only render scattering (to my knowledge). As of the raster path, I haven’t really found any good way to do it outside of disabling certain lighting components and effects, which is definitely more of a hack than it should be.