Volumetric Lighting light pass

Question

I was wondering if anybody could help me with my render settings.

I am trying to render out a light pass (only the lights layer on with everything else as a mask) for some volumetric lighting in my project.

My intention is to add this pass to my after effects file so I can adjust it individually.

my question is - is there a specific way I am supposed to do this? I have a really strong computer, but my render times are nearly 20 minutes a frame. Most other things I render with similar settings render out only take maybe 5 minutes a frame. Even with High reflections.

I have added an atmosphere with a density of .2, my samples are at 1000, my volumetric lighting light samples are all the way down to 0, and the result is looking good, I am just wondering if there was something I could adjust to make it not take so long.

Sorry for the lengthy question, but any help would be greatly appreciated.

Answer 1

What you can do is to separate your scene into two layers

Volume layer: Here there will be the lights and you have to change the material of all the objects to Holdout, you have to check Transparent on the Film menu as well.

Objects layer: Here there will be all the objects with their normal materials and all the lights. Just like your normal scene, but you have to set the density of the Volume world to 0.

Then, in the compositor, you have to do the next:

You can also try the denoising feature to reduce the noise, as well as reducing the step size and Max steps for Volume Sampling in the Geometry menu.

Hope that helps