Fireflies with Environment Map Sampling Resolution Set To "Auto" #72314

New Issue

Steffen Dünner · 2019-12-09T20:39:10+01:00

Steffen Dünner commented

2019-12-09 20:39:10 +01:00

System Information
Operating system: Linux-5.3.15-050315-generic-x86_64-with-debian-buster-sid 64 Bits
Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 440.36

Blender Version
Broken: version: 2.82 (sub 4), branch: master, commit date: 2019-12-09 18:18, hash: 62ef59aa0c and Official 2.81a
Worked: None

Short description of error
Very noisy results with environment maps when using the default "Auto" resolution for the importance map

Exact steps for others to reproduce the error

Open the scene: Fireflies_v01.blend
It's just a simple sphere with a Principled shader on it entirely lit by the 1024x512 pixel "sunset.exr" coming with Blender 2.8x (based on the "Venice Sunset.hdr" available at the HDRIHaven website)
Press F12 and notice the noisy render:
Go to World Properties > Settings > Surface > Sampling and set it to "Manual" and double the resoltion. In this case from 1024 to 2048px
Render again, the result is clean:

The problem becomes more obvious the higher the dynamic range of the HDR / environment is. There are some HDRs where everything works fine OOTB but some are really showing extreme fireflies. I tried to use an HDR coming with Blender for the sake of simplicity but there are examples at HDRIHaven or other sites where the results look much worse than this.
Maybe the "Auto" setting should be set to 2x the horizontal resolution of the HDR?

**System Information** Operating system: Linux-5.3.15-050315-generic-x86_64-with-debian-buster-sid 64 Bits Graphics card: GeForce GTX 1080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 440.36 **Blender Version** Broken: version: 2.82 (sub 4), branch: master, commit date: 2019-12-09 18:18, hash: `62ef59aa0c` and Official 2.81a Worked: None **Short description of error** Very noisy results with environment maps when using the default "Auto" resolution for the importance map **Exact steps for others to reproduce the error** - Open the scene: [Fireflies_v01.blend](https://archive.blender.org/developer/F8202897/Fireflies_v01.blend) It's just a simple sphere with a Principled shader on it entirely lit by the 1024x512 pixel "sunset.exr" coming with Blender 2.8x (based on the "Venice Sunset.hdr" available at the HDRIHaven website) - Press F12 and notice the noisy render: ![Env_Auto.png](https://archive.blender.org/developer/F8202812/Env_Auto.png) - Go to World Properties > Settings > Surface > Sampling and set it to "Manual" and double the resoltion. In this case from 1024 to 2048px ![Screenshot from 2019-12-09 20-28-36.png](https://archive.blender.org/developer/F8202820/Screenshot_from_2019-12-09_20-28-36.png) - Render again, the result is clean: ![Env_2048.png](https://archive.blender.org/developer/F8202823/Env_2048.png) The problem becomes more obvious the higher the dynamic range of the HDR / environment is. There are some HDRs where everything works fine OOTB but some are really showing extreme fireflies. I tried to use an HDR coming with Blender for the sake of simplicity but there are examples at HDRIHaven or other sites where the results look much worse than this. Maybe the "Auto" setting should be set to 2x the horizontal resolution of the HDR?

Steffen Dünner commented

2019-12-09 20:39:10 +01:00

Added subscriber: @SteffenD

Steffen Dünner commented

2019-12-11 01:12:27 +01:00

Here's a blend file that more clearly shows the problem (also based on a CC0 texture from HDRI Haven).
Just press F12 and see the fireflies, now switch the sampling to "Manual" (which I set to 2048 = twice the horizontal resolution of the environment map) and all is fine with the same amount of samples and no clamping needed.

Fireflies_v02.blend

Here's a blend file that more clearly shows the problem (also based on a CC0 texture from HDRI Haven). Just press F12 and see the fireflies, now switch the sampling to "Manual" (which I set to 2048 = twice the horizontal resolution of the environment map) and all is fine with the same amount of samples and no clamping needed. [Fireflies_v02.blend](https://archive.blender.org/developer/F8207160/Fireflies_v02.blend)

Steffen Dünner commented

2019-12-11 01:15:43 +01:00

With "Auto" samples:

With "Manual" samples set to twice the horizontal resolution:

With "Auto" samples: ![Screenshot from 2019-12-11 01-01-57.png](https://archive.blender.org/developer/F8207169/Screenshot_from_2019-12-11_01-01-57.png) With "Manual" samples set to twice the horizontal resolution: ![Screenshot from 2019-12-11 01-02-17.png](https://archive.blender.org/developer/F8207173/Screenshot_from_2019-12-11_01-02-17.png)

Jacques Lucke commented

2019-12-29 16:48:49 +01:00

Added subscribers: @brecht, @JacquesLucke

Jacques Lucke commented

2019-12-29 16:48:49 +01:00

Changed status from 'Needs Triage' to: 'Archived'

Jacques Lucke closed this issue

2019-12-29 16:48:49 +01:00

Jacques Lucke self-assigned this 2019-12-29 16:48:49 +01:00

Jacques Lucke commented

2019-12-29 16:48:49 +01:00

I don't know what "Auto" is doing exactly. I'm not sure if the default settings for cycles have to provide a noise free result. I'd guess that for any resolution it is possible to find examples that result in a noisy result, but I'm not sure.

I don't think this is a bug, so I'm closing this.
@brecht, do you think the behavior of "Auto" should be changed as described above?

I don't know what "Auto" is doing exactly. I'm not sure if the default settings for cycles have to provide a noise free result. I'd guess that for any resolution it is possible to find examples that result in a noisy result, but I'm not sure. I don't think this is a bug, so I'm closing this. @brecht, do you think the behavior of "Auto" should be changed as described above?

Steffen Dünner commented

2019-12-30 17:53:17 +01:00

Hi there!

I know it's not a high priority issue as I can always do it the "old skool" way and set the resolution manually.
I just thought it was worth reporting here because now that Blender 2.8 is getting a lot of attention and new users, the feature (set to "Auto" by default) might cause a lot of reports and disappointment. I have some HDR environments that show a lot more fireflies than the ones I posted. They might be special cases or rather extreme, but if it even happens with the HDRs coming with Blender, that will cause trouble IMHO.

@JacquesLucke : The "Auto" settings just takes the horizontal resolution of an image and uses it as the "Map Resolution".
I can post some example HDRs that completely change the look of a render if set to "Auto" compared to "Manual" set to double the horizontal resolution.

Hi there! I know it's not a high priority issue as I can always do it the "old skool" way and set the resolution manually. I just thought it was worth reporting here because now that Blender 2.8 is getting a lot of attention and new users, the feature (set to "Auto" by default) might cause a lot of reports and disappointment. I have some HDR environments that show **a lot** more fireflies than the ones I posted. They might be special cases or rather extreme, but if it even happens with the HDRs coming with Blender, that will cause trouble IMHO. @JacquesLucke : The "Auto" settings just takes the horizontal resolution of an image and uses it as the "Map Resolution". I can post some example HDRs that completely change the look of a render if set to "Auto" compared to "Manual" set to double the horizontal resolution.

Emir Sinan Gürlek commented

2020-02-26 01:19:06 +01:00

Added subscriber: @filibis

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Fireflies with Environment Map Sampling Resolution Set To "Auto" #72314