Adaptive Domain creates lines in smoke #74559
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Reference: blender/blender#74559
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System Information
Operating system: Win 10
Graphics card: Dual RTX Titans
Blender Version
Broken: Blender 2.82
Short description of error
With adaptive domain enabled, noticeable horizontal (and sometimes vertical) lines appear in the smoke
weird lines.mp4
Exact steps for others to reproduce the error
Simple blend file:
Turn off adaptive. Not only will the smoke move faster creating a totally different looking simulation (which is problem in itself) but the lines will be gone:
It's most noticeable when the domain is large, and the adaptive box is only a small portion of it.
Increasing the adaptive margin to 24 helps somewhat, but it's still there. Any higher and it defeats the purpose of adaptive - baking takes as long as just turning it off.
Sample blend:
adaptive bug2.blend
Added subscriber: @AndrewPrice
Added subscriber: @johny.zlo
Added subscriber: @ankitm
https://developer.blender.org/T67356#867120 are these the same reports? does the last comment by Germano help ?
No this is separate. The lines are part of the simulation, not the shader.
It's most obvious at the end of the video above, as you can see it creates waves in the plumes.
https://docs.blender.org/manual/en/latest/physics/fluid/type/domain/gas/adaptive_domain.html?highlight=adaptive%20domain
I still think this is expected behaviour.. Adaptive domain saves some computation time by shrinking the gas boundary. Increasing margin gives more space to the gas, thus more computation, thus it undercuts the main benefit of AD: save computation time.
bottomline: it's a tradeoff between time saving and accuracy (accidental Heisenberg? )
Added subscriber: @iss
Changed status from 'Needs Triage' to: 'Needs User Info'
This is effect of low domain resolution most likely
https://docs.blender.org/manual/en/dev/physics/fluid/type/domain/settings.html#bpy-types-fluiddomainsettings-resolution-max
Try to increase and see if issue persists.
Please provide sample file so we can actually see problem in action.
Added subscriber: @sebbas
@iss Changing the resolution doesn't change much. It just makes the gaps between the lines smaller:
@ankitm I'd be surprised if this was the expected behaviour. If it only expands after it's needed, rather than preemptively based on the movement of the smoke then it should never be used. Coz it will always interrupt the smoke and create a totally different simulation than when disabled.
@sebbas I wonder if it's related to the Adaptive Time Steps bug , not computing multiple times between frames to create the right sized adaptive domain?
Also I've attached the .blend to the OP.
Changed status from 'Needs User Info' to: 'Confirmed'
Added subscriber: @BeckersC
Added subscriber: @GottfriedHofmann
I can confirm as well - the results are completely different with and without adaptive domain even though they should be identical.
@GottfriedHofmann did you discuss it with Sebastian already?
Yes :-)
Added subscriber: @deadpin
Are .blends from 2.82 supposed to be usable in 2.83? I can't get the attached .blend to work in recent builds (after bake). Wanted to see if things improved here.
Added subscriber: @Adam-Burke
The problem where the old .blend didn't open has been resolved (was because it was set to openvdb/modular format). However, the issue with the lines and completely different looking simulation still seem present :-/
Added subscriber: @Iago-Diogo-de-Vasconcelos-Mota
Any update on this? Sean Kennedy also ran into it.
Been working on other areas lately. The adaptive domain is really causing lots of problems, so now is probably a good time to look at it again.
Just pushed
62a819202ewhich should improve the adaptive domain in general. In my tests I noticed that the "cutting-off" issue seems to be solved.Maybe everyone from this thread can try out the latest master and report their findings?
There will be one more improvement commit for the adaptive domain to hopefully improve some of the blockiness - but that's just fyi.
Added subscriber: @Creavite
Added subscriber: @SeanKennedy
Nice! I'll give it a try tomorrow once the builds are updated with the new fix.
Today's Blender build still seems to have the issue. This is with Adaptive Domain turned on, I didn't try with it turned off yet.
Added subscriber: @Gadas
Any update on this one? I just tested it in 2.9 using the bug blend file attached in OP and it's still happening.
It's bug sprint week and a good time to look into this again.
My new computer arrives in a week, if there's anything I can test for you after that, please just ask. Excited to improve this!
An update! @AndrewPrice @SeanKennedy can you try out the latest state of the master branch (
8720c66009)?In my test the example scene from this report behaved much better. Would be interesting to see how some of your other scenes perform.
Yep, the example scene is looking a lot better! There are still some occasional lines, though:
But, those could be reduced by increasing the margin, after which, I ended up with this:
So maybe part of the issue could be related to smoke getting too close to the bounds?
Just tried it in 2.91 using the .blend from the OP and am still seeing lines.
@sebbas Are you testing your patches on the .blend from the OP?
I also get the lines with the OP blend file
I also tried adjusting the adaptive domain threshold, but didn't get results that were better. I tried @Iago-Diogo-de-Vasconcelos-Mota 's suggestion about adjusting the margin, as well. Those first 3 screenshots are with the margin set at 4.
This one is margin of 2
This one is margin of 24
So I got lines no matter what the margin was set to.
Added subscriber: @jwu420
Added subscriber: @god1ged
Hello, you mean this is still not solved right ?
Correct. Still unsolved.
@sebbas have you had a chance to revisit it yet?
Added subscriber: @alexisrivera
Guys, I have the same lines as the video posted here by Andrew, I thought It was my computer until I found this topic
0001-0050.mp4
Is there any update on this?
Added subscriber: @ChristophWerner
Nope.
Checked it today in Blender 3.0 daily build.
Added subscriber: @MichaelHermann
Added subscriber: @Raimund58
Added subscriber: @zebus3dream
Hello guys. I'm having the same problem with both Blender 3.5 (open VDB or native smoke sim) and Cinema 4D's 2023.2 Pyro as well.
The first two images are C4D's viewport. The resolution is set really high there, but nothing matters, I get the pattern all the same. The 3rd image is from Blender's (cycles render) smoke sim, 96 res and no adaptive domain.
The video (Blender, Cycles render) is an open VDB from Embergen's default explosion template, the pattern appears in the fire once I render it in Blender.
So I'm having this pattern everywhere, regardless of resolution. Anyone know what it could possibly be?
Still seeing this in 3.6, anyone have any updates or fixes that make it less noticeable?