Resimulation's Effect on Rendering

[joshclos]

I'm curious if there is a mathematical process to get the values of an amplified resolution resimulation to render similar to the original simulation (just in terms of fire/smoke values).

For example, my sim has roughly 22milion voxels and was resimulated with an amplification of 1.0, so now the new amplified sim is roughly 183million. Using the render settings from the 22million grid results in a large difference in fire brightness and levels (the 183 million grid appears much more dim and less overall super bright values). Currently I'm arbitrarily increasing some of the values like "Fire Multiplier" and "Smoke Opacity" until they look more like the other but maybe someone knows a mathematical equivalent.

Any advice is appreciated!

Thanks!
Josh

[Svetlin.Nikolov]

Hey,

For the smoke opacity, this should be handled by the "Scale Opacity by Scene Units" option.

However, for the Fire opacity and intensity I'm talking off the top of my head, but I think in Own Opacity and Use Smoke Opacity mode it would scale correctly after upres, but Fully Visible wouldn't scale properly. Do you happen to use Fully Visible fire opacity?

Cheers!

[joshclos]

Hey,

Do you happen to use Fully Visible fire opacity?

Cheers!

Yep, that's right I'm using Fully Visible. I ended up increasing the fire multiplier from 4 to 250 and it's closer to the original values.

Thanks!

[Svetlin.Nikolov]

Roger that, I'll take a look and see how to rescale it automatically.

Cheers!

[joshclos]

Just a note - I've been doing renders with the "Use Own Opacity" option now and the same issue occurs during resimulation - the renders of the resimulated grid are much darker. I've been increasing the fire multiplier to 200 or 300 to get a similar look. It is a little strange though because I am getting more resolution of course but I'm losing a bit of the fire detail before, which now renders as smoke. Possibly due to the resimulation mismatch. Hmm. Hopefully I can reproduce this issue at home so I can send a screenshot.

[Svetlin.Nikolov]

Oh, copy that. I will try to repro it here in a few days, just gotta finish some stuff first. You should be able to change the resolution without affecting the rendering, so if anything needs fixing, we have to do it quickly...

Cheers!