Studiolight HDRI cause fireflies in Cycles #73832

New Issue

Irfan Celik · 2020-02-15T12:02:49+01:00

Irfan Celik commented

2020-02-15 12:02:49 +01:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.28

Blender Version
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: 77d23b0bd7
Worked: (optional)

Short description of error
Some of the built in HDRI contain negative values which can cause fireflies in Cycles.
Only forest.exr and studio.exr seem to be fine.

Exact steps for others to reproduce the error
Included is the original "city.exr" from HDRI Haven but resaved in Blender using the DWAA compression.
Install new HDRI in Blender.
Open attached blend file.
Switch top view to city.exr using Cycles viewport rendering.
Switch bottom view to included portland_landing_pad_1k_compressed.exr

Here is a screenshot of the problem:

studiolight_hdr_fireflies.blend

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.28 **Blender Version** Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: `77d23b0bd7` Worked: (optional) **Short description of error** Some of the built in HDRI contain negative values which can cause fireflies in Cycles. Only forest.exr and studio.exr seem to be fine. **Exact steps for others to reproduce the error** Included is the original "city.exr" from HDRI Haven but resaved in Blender using the DWAA compression. Install new HDRI in Blender. Open attached blend file. Switch top view to city.exr using Cycles viewport rendering. Switch bottom view to included portland_landing_pad_1k_compressed.exr ![studiolight_hdr_fireflies2.jpg](https://archive.blender.org/developer/F8341098/studiolight_hdr_fireflies2.jpg) Here is a screenshot of the problem: ![studiolight_hdr_fireflies.jpg](https://archive.blender.org/developer/F8341104/studiolight_hdr_fireflies.jpg) [studiolight_hdr_fireflies.blend](https://archive.blender.org/developer/F8341109/studiolight_hdr_fireflies.blend) ![portland_landing_pad_1k_compressed.exr](https://archive.blender.org/developer/F8341126/portland_landing_pad_1k_compressed.exr)

Irfan Celik commented

2020-02-15 12:02:49 +01:00

Added subscriber: @irfancelik

William Reynish commented

2020-02-15 16:20:01 +01:00

Added subscriber: @WilliamReynish

William Reynish commented

2020-02-15 16:20:01 +01:00

Thanks for this. Have you also checked the other included HDRIs?

Irfan Celik commented

2020-02-15 22:13:39 +01:00

I checked all of them and only forest and studio seem to be ok.
I can try to find all of them on HDRI Haven and post them here with DWAA compression if that helps.

I checked all of them and only forest and studio seem to be ok. I can try to find all of them on HDRI Haven and post them here with DWAA compression if that helps.

Irfan Celik commented

2020-02-15 23:39:42 +01:00

So I found all of them and resaved them as DWAA exr files but the total file size is now 4.75mb compared to 1.8mb before.
I have no idea what kind of compression was used before. I can upload the new ones here if you want.

So I found all of them and resaved them as DWAA exr files but the total file size is now 4.75mb compared to 1.8mb before. I have no idea what kind of compression was used before. I can upload the new ones here if you want.

Richard Antalik commented

2020-02-17 10:43:45 +01:00

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

Bastien Montagne commented

2020-02-17 15:27:51 +01:00

Added subscriber: @mont29

Bastien Montagne commented

2020-02-17 15:27:51 +01:00

Not sure this actually belongs here, or if the issue is actually with those HDR files? is Cycles supposed to support negative values in HDR images? What would be the meaning of those?

Brecht Van Lommel commented

2020-02-17 15:30:39 +01:00

Closed as duplicate of #69745

Brecht Van Lommel closed this issue

2020-02-17 15:30:39 +01:00

Irfan Celik commented

2020-02-17 15:35:10 +01:00

It is not a Cycles problem. The HDR files just contain negative values which they should not in any case. Probably happened while over sharpening or extreme compression.
I still don´t know what method was used before because I could not reproduce that kind of compression in either Blender or Natron. The exr files I got are unfortunately at least twice the size then the ones shipping with Blender.

It is not a Cycles problem. The HDR files just contain negative values which they should not in any case. Probably happened while over sharpening or extreme compression. I still don´t know what method was used before because I could not reproduce that kind of compression in either Blender or Natron. The exr files I got are unfortunately at least twice the size then the ones shipping with Blender.

Brecht Van Lommel commented

2020-02-17 15:35:33 +01:00

Added subscriber: @brecht

Brecht Van Lommel commented

2020-02-17 15:35:33 +01:00

Negative values normally should not exist, but they can happen with some downscaling algorithms.

We could use a different scaling algorithm or clamp the pixel values for the bundled HDRIs, but it doesn't really solve the general problem. We need to fix the Cycles environment not to be so noisy when a very low and very high pixel value are right next to each other, for which we have another task.

Negative values normally should not exist, but they can happen with some downscaling algorithms. We could use a different scaling algorithm or clamp the pixel values for the bundled HDRIs, but it doesn't really solve the general problem. We need to fix the Cycles environment not to be so noisy when a very low and very high pixel value are right next to each other, for which we have another task.

Irfan Celik commented

2020-02-17 15:42:44 +01:00

Just as a note, the 1k resolution HDR files from HDRI Haven do not show those artifacts.

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Studiolight HDRI cause fireflies in Cycles #73832