Lightcache speed up at 0 vs off

[japetus]

Trying to do a shot of some ships flying through some dense-ish clouds. Was trying out some tips from here (https://docs.chaosgroup.com/m/mobile...#page/50990522). As you can imagine, the rendering is pretty slow going through some clouds. I'm trying to use some Phoenix simmed clouds instead of Fog, the sim is good, but the render time is very slow. I'm using Raytrace-GI since that gives the most cloud-like look accoruding to the tuts. Since I'm traveling through the clouds, lightcache splotches are very visible, so I set lightcache speed up to 0, still visible. I turn it off, my render times sky rocket of course. My question at this point is, since the speedup is set to 0, is there more control over light cache splotches, like changing the Lightcache settings themselves? Is the speedup acting like a multiplier? I was surprised to find that even at 0, light cache speedup ON is still way faster than it off. Would it be a matter of decreasing the step values?

[Joelaff]

Yeah, I always thought that was a little weird.

[Svetlin.Nikolov]

Hey,

If you reduce your speedup to 0 and there's still artifacts, you gotta turn off your light cache and go to the Max atmosphere settings where you should enable probabilistic volumetrics.

The speedup is not a multiplier indeed - it's a way to speedup the volume light cache. At 0, the volume light cache is its native "unbiased :P" form. But it's still caching, which is very different from having the cache off completely.

Cheers!

[Joelaff]

Thanks for the clarification, Svetlin.

Probablistic indeed helps a lot for clouds.