Mantaflow - Enabling "Noise" breaks fast-moving smoke #78738

New Issue

Iago Mota · 2020-07-08T16:07:43+02:00

Iago Mota commented

2020-07-08 16:07:43 +02:00

System Information
Operating system: Windows 10
Graphics card: Nvidia GeForce GTX 650 Ti
Processor: Intel® Core™ i7-3770

Blender Version
Broken: 2.83.0
Worked: Never

Short description of error
Enabling noise on fast-moving smoke produces a "grainy" result that doesn't match original simulation.
C - High Speed Noise - Demo.mp4

Also, this problem is less profound when the cache type is set to "Final", though still clearly visible.

Exact steps to reproduce the error

In any smoke simulation, dramatically increase the velocity of the smoke, either in the emitter settings, or with a force-field.
Bake Data
Bake Noise

Noise on High-Speed Smoke.blend

**System Information** Operating system: Windows 10 Graphics card: Nvidia GeForce GTX 650 Ti Processor: Intel® Core™ i7-3770 **Blender Version** Broken: 2.83.0 Worked: Never **Short description of error** Enabling noise on fast-moving smoke produces a "grainy" result that doesn't match original simulation. [C - High Speed Noise - Demo.mp4](https://archive.blender.org/developer/F8678280/C_-_High_Speed_Noise_-_Demo.mp4) Also, this problem is less profound when the cache type is set to "Final", though still clearly visible. **Exact steps to reproduce the error** 1. In any smoke simulation, dramatically increase the velocity of the smoke, either in the emitter settings, or with a force-field. 2. Bake Data 3. Bake Noise [Noise on High-Speed Smoke.blend](https://archive.blender.org/developer/F8678291/Noise_on_High-Speed_Smoke.blend)

Iago Mota commented

2020-07-08 16:07:43 +02:00

Added subscriber: @Iago-Diogo-de-Vasconcelos-Mota

Ankit Meel commented

2020-07-08 21:49:03 +02:00

Added subscriber: @ankitm

Ankit Meel commented

2020-07-08 21:49:03 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Ankit Meel commented

2020-07-08 21:49:03 +02:00

Is the behaviour same on 2.90 ? https://builder.blender.org/download/

Iago Mota commented

2020-07-09 03:59:41 +02:00

For some reason, in the newest build of 2.9, the simulation isn't at all visible after baking the noise, so I tried this on a previous build instead: 2.90 - c8060a78fd . And, yes, unfortunately the issues persist. Bv2.9 Noise on High-Speed Smoke.blend
The smoke moved a lot slower in 2.9, so I ended-up using a wind force-field to really accelerate it.
By the way, these issues were also present in 2.82.0 Bv2.82 Noise on High-Speed Smoke.blend

For some reason, in the newest build of 2.9, the simulation isn't at all visible after baking the noise, so I tried this on a previous build instead: 2.90 - c8060a78fdf3 . And, yes, unfortunately the issues persist. [Bv2.9 Noise on High-Speed Smoke.blend](https://archive.blender.org/developer/F8679594/Bv2.9_Noise_on_High-Speed_Smoke.blend) The smoke moved a lot slower in 2.9, so I ended-up using a wind force-field to really accelerate it. By the way, these issues were also present in 2.82.0 [Bv2.82 Noise on High-Speed Smoke.blend](https://archive.blender.org/developer/F8679600/Bv2.82_Noise_on_High-Speed_Smoke.blend)

Ankit Meel commented

2020-07-09 11:37:26 +02:00

Changed status from 'Needs User Info' to: 'Confirmed'

Jacques Lucke commented

2020-07-13 14:25:12 +02:00

Added subscribers: @sebbas, @JacquesLucke

Jacques Lucke commented

2020-07-13 14:25:12 +02:00

I cannot see the smoke after baking the noise either...
I can see the issue when setting the cache type to "All" though.

Maybe the issue with high velocity noise is an artifact of the algorithm, I don't know. In that case, it might be a known issue. @sebbas might know more.

I cannot see the smoke after baking the noise either... I can see the issue when setting the cache type to "All" though. Maybe the issue with high velocity noise is an artifact of the algorithm, I don't know. In that case, it might be a known issue. @sebbas might know more.

Sebastián Barschkis commented

2020-07-21 12:43:09 +02:00

@Iago-Diogo-de-Vasconcelos-Mota Can you try out this scene with the latest master? I pushed some update for smoke noise and, at least in my first tests, regular smoke and noise seem to "match" much better now.

Iago Mota commented

2020-07-22 03:32:11 +02:00

@sebbas Thank you for the update! Unfortunately, I'm still seeing the problem in 2.90.0 607d745a79 . Though, in my opinion, it already seems less pronounced than in 2.83.2.

@sebbas Thank you for the update! Unfortunately, I'm still seeing the problem in 2.90.0 607d745a79e0 . Though, in my opinion, it already seems less pronounced than in 2.83.2.

Richard Antalik commented

2020-09-29 18:37:58 +02:00

Added subscriber: @iss

Richard Antalik commented

2020-09-29 18:37:58 +02:00

This static noise issue is reported in #81017, if you want separate report for that. Otherwise we can merge these reports.

Iago Mota commented

2020-09-30 02:52:52 +02:00

@iss Yeah, I'm not sure if these are related issues, so I'll keep them separate for now to avoid confusion. Thanks!

Dalai Felinto commented

2022-05-09 11:01:55 +02:00

Mantaflow (fluid simulator) has no active developer at the moment. Moving those bugs as known issues so at least other users can find their issues already reported.

Philipp Oeser removed the

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Mantaflow - Enabling "Noise" breaks fast-moving smoke #78738