Lots of lights + Global volume Mtl - Any settings i can tweak?

[Jpjapers]

I have a scene with probably between 100 and 200 light sources and they all need some volumetric effects to show beams (I cant use the Volume light effect for reasons).
Its a bit of a nightmare scenario for a renderer im sure but after a 12hr render on a 3950X at 1440p the volume fog is still insanely noisy and full of fireflies.
Denoising helps a little but only if cranked up to 100%.

Are there any system adjustments i can make to corona to improve the rendering in this situation? I have 128GB RAM so thats not an issue.
Are there any scene optimisations i can make?

[TomG]

Things you can try on your already finished render - scaling with an AI scaler like Topaz can help; as can denoising with things like Topaz, or Neat (it's a video denoiser but should be able to get it to work on a still). Those may give great results on your image without any need to re-render - but the downside is they do cost money as extra applications. I doubt there are any scene changes that will "cut render times in half" or something dramatic, which is why I suggest this as an option to explore.

[Jpjapers]

Things you can try on your already finished render - scaling with an AI scaler like Topaz can help; as can denoising with things like Topaz, or Neat (it's a video denoiser but should be able to get it to work on a still). Those may give great results on your image without any need to re-render - but the downside is they do cost money as extra applications. I doubt there are any scene changes that will "cut render times in half" or something dramatic, which is why I suggest this as an option to explore.

Ill be re-rendering this image anyway as this was a trial run to gauge how long id need to render the final thing at higher res and at this point im skeptical as to whether corona would ever actually clean the noise up even if i left it for a week. I dont think this is a thing but are there any ways to exclude certain lights from volumetric calculations? Given its not a fake post process effect id imagine not but it would certainly be a great feature to have especially if you could split out specific lights into different volumetric passes which again i cant see a way to do but correct me if im wrong!

[TomG]

You can exclude lights from volumetrics if you use an object with Volumetric material applied (cube that encompasses whole scene, or whatever part needs volumetrics anyway) rather than a Global Volume, as then you can add that object to the exclude list in the Corona lights.

[Jpjapers]

You can exclude lights from volumetrics if you use an object with Volumetric material applied (cube that encompasses whole scene, or whatever part needs volumetrics anyway) rather than a Global Volume, as then you can add that object to the exclude list in the Corona lights.

Of course!! If i duplicated the box in place and excluded separate lights so each box was only showing a subset of volumetric, is there any way to split those volumetric passes out into separate render passes?

[TomG]

There's a volumetrics pass, but that's all volumetrics in one place and I think you are asking about those different volumetric objects appearing separately. But I think if you swap things around and use an INCLUDE list, then LightMix will do the trick - Corona Light only includes the volumetric object, then its LightMix will in effect be just that light's volumetric effects. If the light does have to illuminate other objects in the scene, you could duplicate it and have the duplicate exclude the volumetric object this time, then you have a LightSelect for the volumetrics only, and one for the non-volumetrics only. Not sure if that's what you're looking for though....

[burnin]

All I found was, there's absorption/scattering threshold which, when passed causes image rendering never to clear. It's quite finicky to handle. Volume set to single bounce helps too. 

~1:23 h on AMD TR1950X, 225x lights in a volume, no post, just in lens camera fx

[Jpjapers]

There's a volumetrics pass, but that's all volumetrics in one place and I think you are asking about those different volumetric objects appearing separately. But I think if you swap things around and use an INCLUDE list, then LightMix will do the trick - Corona Light only includes the volumetric object, then its LightMix will in effect be just that light's volumetric effects. If the light does have to illuminate other objects in the scene, you could duplicate it and have the duplicate exclude the volumetric object this time, then you have a LightSelect for the volumetrics only, and one for the non-volumetrics only. Not sure if that's what you're looking for though....

That's a very interesting workaround! I might give that one a try. Thanks Tom