Hmm, do you really need Volumetric Geometry mode? It will slow the rendering quite a lot, so if this is not a pass you’ll need render elements from, you can switch to Volumetric to speed things up. However, 2 mins for this sim are still quite a lot - what is your grid resolution? Are you using Phoenix 3.05 or a later nightly? If possible, can we have a look at the scene so we can profile it and figure out if something can be improved?
Hey, thanks for the scene! So the light material is indeed slowing the render quite a lot. What you can do on the Phoenix side:
- Increase the Phoenix Light Cache speedup - right now it’s 0.9 and you can keep increasing it until you see artifacts, but this is the strongest speed boost you can get.
- Increase the Shadow Step - since you don’t have much shadow detail, you can overcook this.
- Enable the V-Ray → Overrides → Volumetrics → Probabilistic Volumetrics - here you can also experiment with the samples - note that high samples would be slow because too much unneeded rays will be cast and low samples will be slow because there will be too much noise to converge, so the ideal value would be in the middle.
Ah yes - another way you could approach the problem would be to turn off the Phoenix Light Cache completely and render with or without Probabilistic Volumetrics - this way the smoke would be noisier and it would be up to the V-Ray settings to clear the image.
If you have to go so much down on the speedup, try the alternative approach - turn off the Phoenix light cache completely, try rendering like that and then try enabling the Probabilistic Volumetrics option.
I tried to turn on the probabilistic volmetrics option in v-ray render setting, but it doesn’t seem to affect the render at all, whether if I turn it on or off, sample 20 or sample 1000
In this case, I guess it’s up to the V-Ray guys to try to optimize the light material since it’s significantly slower than a regular light - I already pinged them about it.
