Maya Fluids Textures and artefacts

[Anonymous]

It's been a while I used Maya Fluids - , but my current gig requires going old school. Doing some quick tests and I am running into some issues.

Some questions about the attached images. 

(1) How do I get rid of these holes in my smoke cloud?

(2) The fluid looks blocky despite using the cubic filter type. Increasing step size is not mitigating this issue.

(3) How would I get those cellular like density/smoke patterns over the fireball like here: https://images.hamodia.com/…/2016/12/Haifa-fire-1024x683.jpg
No matter what I try with the textures, they always look smeared/vertical, not cellular and billowy (even with the billow texture type)

I am rendering with Arnold
My container is 
res 200
size 25/30/50

Thanks!

[mspeer]

Hi!

The blocking artifacts is just a problem of a too high contrast between density values for some cells.

If 1 is fully opaque and 0 transparent and you have a cell with value 10 and the next one with 0, then for all interpolated values like 9, 8, 7, 6 you will get fully opaque.

For the other problems this is a combined effect of fluid density * texture density.

Without doing a complete tutorial i can only suggest to test this with a simpler setup maybe in 2D to get familiar with the textures and the combined effect.

You also may consider not to use textures for your Fluids. While simulation may need more time, rendering will be a lot faster without textures (and animation will look more realistic). However this does not apply if you are doing stills.

[Anonymous]

Hello Marko, 

The blocking artifacts is just a problem of a too high contrast between density values for some cells.

So this can be resolved by adjusting the opacity curve (ie less sharp curves)?

You also may consider not to use textures for your Fluids. While simulation may need more time, rendering will be a lot faster without textures (and animation will look more realistic). However this does not apply if you are doing stills.

You mean simulating at higher resolution? How would I get those cellular patterns over the fireball then? I have been having some success by duplicating/overlapping emitters - where one emitter only emits density (smoke), to mimic those patterns, but it seems textures would be perfect to achieve this. They are just hard to control IMO.

[mspeer]

Hi!

"So this can be resolved by adjusting the opacity curve (ie less sharp curves)?"

Yes, every opacity/density control can help to resolve this.

"You mean simulating at higher resolution?"

Yes. You also can test different settings for High Detail Solve, Grid Interpolator, Turbulence.

In real world a fire or explosion is affected by a lot of things, so you have to rebuild or fake this in your simulation (wind, different material burning types, multiple sources for heat, ...).