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Volume / VDB optimisation

Unread postPosted: Mon Oct 14, 2019 10:31 am
by metalrahul
Is there any other factors other than volume samples in path tracer or optimisation settings in the individual volume objects (Camera / Secondary / Primary etc) to bring down the render times with Volumes?

I have quite few Volumes / VDB layers in my scene and with them turned on, my render times are unreasonably slow (more than 5 or 6 hours per frame. 2k) and when I turn them off then I can get a frame rendered in an hour or 2. I have an AMD Rayzen 7 with 32 Gig RAM.

Does the physical scale of the volume box or VDB matters or is there any other settings that I missing? As of now my individual volume settings are at 5%, Primary and Secondary at 50% and Volume samples 1 on Path Tracers.

Re: Volume / VDB optimisation

Unread postPosted: Mon Oct 14, 2019 10:50 am
by dboude
Hi,

Yes, there are. Volumes by default are evaluated in the Gi, reflection, refraction etc... Try to check unseen by Gi, by reflection etc.. on volume objects.

Cheers ;)

Re: Volume / VDB optimisation

Unread postPosted: Mon Oct 14, 2019 1:58 pm
by metalrahul
Thanks Damien, I will give it a try once I get home and let you know!

Re: Volume / VDB optimisation

Unread postPosted: Mon Oct 14, 2019 3:33 pm
by sam
And set the Diffuse Depth attribute of the volume material to 0. By default, it is evaluating multiple scattering which is very expensive.

Re: Volume / VDB optimisation

Unread postPosted: Tue Oct 15, 2019 2:04 pm
by tom_tm
And for quicker loading time and display in the progressive renderer, you can also deactivate VDB Load Delay in the Preferences.

Re: Volume / VDB optimisation

Unread postPosted: Thu Oct 17, 2019 3:28 pm
by metalrahul
Thanks for the tips Sam and Tom, I do will do some tests since I wasn't satisfied with render times even after switching off GI, Refraction, Reflection and SSS.

Re: Volume / VDB optimisation

Unread postPosted: Fri Oct 18, 2019 6:49 pm
by ambassador1
You can render them as a separate pass for comp, with a volume specific path tracer with much lower render settings and get decent quality, along with the ability to de noise them in post. We can render vdb's at %15-30 sampling quality for final output after denoise in comp, you can even try the built in deNoise. If you are trying to get final quality on geo/textures/shading and volumes in a single render, its generally not going to be a quick render. A separate pass will also give more control in post.