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Fuzzy flames problem

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hochenauer
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Hi, i´m working on a pyro sim, where a person starts burning.

I based it more or less on the spreading fire shelf tool.
It behaves quite well as expected, but i get a kind of fuzzy look, which i can´t pinpoint where it comes from.

The scene should be in scale and all the voxel parameters are set to 0.0045, should i go lower?
When i try to get lower the sim get´s stuck.
My machine is quite ok, it should handle this, i guess.

I attached a simplified version of the scene, thanks your for any tips.
best wishes

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fuzzy_flame.jpg (399.5 KB)
fuzzy_fire.hiplc (1.3 MB)

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hochenauer
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Here another screenshot, where the problem is even more visible, it also appears in rendering.

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fuzzy_flame_02.jpg (224.7 KB)

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ati
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The fuzziness has nothing to do with the resolution. I can even lower the resolution. The reason is your disturbance force, you basically applying a very strong disturbance all across the fluid container.

I adjusted your setup a bit to get nicer looking fire. Let me know if you need further explanation.

Also try to use ACES, which will give you a much nicer looking fire on default.

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fuzzy_fire_mod.hiplc (1.5 MB)

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ati
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This is what you should see with the modified scene using the ACES workflow.
Edited by ati - Dec. 4, 2020 15:51:27

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fire.png (514.8 KB)

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hochenauer
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Thank you so much for putting the time into answering:
i was ramping different parameters, but i hit a dead end.
This looks so much better and also explains, why simply more resolution won´t give a better result.

As for using Aces with pyro/houdini:
I´m also a color grader, so i know Aces, but could you point me to the right direction how to implement it.

thank you, you just saved my weekend
Edited by hochenauer - Dec. 4, 2020 16:30:41
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jsmack
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hochenauer
Thank you so much for putting the time into answering:
i was ramping different parameters, but i hit a dead end.
This looks so much better and also explains, why simply more resolution won´t give a better result.

As for using Aces with pyro/houdini:
I´m also a color grader, so i know Aces, but could you point me to the right direction how to implement it.

thank you, you just saved my weekend

Download the latest configs from your github repo of choice, or build it your self from source.

https://github.com/colour-science/OpenColorIO-Configs/releases/tag/v1.2 [github.com]

Then export the path to the config as $OCIO in your environment. (how depends on your OS, but if only needed in Houdini, then it can be set in the houdini.env)
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ati
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Exactly as jsmack said.
There is also a doc written for this as well:

https://www.sidefx.com/docs/houdini/pyro/shading.html [www.sidefx.com]
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hochenauer
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I was following filmic blender, since it came out. I think it should be incorporate in all 3d packagages as a standardized workflow.
I wasn´t aware that development kept up with houdini, thanks for the pointers!
thanks for pointing that out.
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