Regression: Cycles: Weird Mesh Light Sampling #112931

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opened 2023-09-27 02:50:00 +02:00 by Alaska · 6 comments

Alaska commented

2023-09-27 02:50:00 +02:00

Member

System Information
Operating system: Windows-10-10.0.22621-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 537.42

Blender Version
Broken: version: 4.0.0 Alpha, branch: main, commit date: 2023-09-26 06:58, hash: 3514d6ed52a3
Worked: 3.5.X, and likely 3.6.X

Short description of error
Mesh lights show weird sampling patterns. Most noticeable when the bounding box of the mesh light intersects with a surface.

Exact steps for others to reproduce the error
Download attached file and render it in Cycles. Then compare it to previous versions of Blender.

If you need to make this scene from scratch:

Create a plane. This is the ground.
Create another plane, this is our mesh light, and rotated it 45 degrees so it intersects with the ground.
Give the mesh light plane an emission shader and render it in Cycles.

**System Information** Operating system: Windows-10-10.0.22621-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 537.42 **Blender Version** Broken: version: 4.0.0 Alpha, branch: main, commit date: 2023-09-26 06:58, hash: `3514d6ed52a3` Worked: 3.5.X, and likely 3.6.X **Short description of error** Mesh lights show weird sampling patterns. Most noticeable when the bounding box of the mesh light intersects with a surface. ![Example sampling pattern.png](/attachments/0fe0e191-cf95-447b-a0e6-4ab43c17f1e7) **Exact steps for others to reproduce the error** Download attached file and render it in Cycles. Then compare it to previous versions of Blender. If you need to make this scene from scratch: 1. Create a plane. This is the ground. 2. Create another plane, this is our mesh light, and rotated it 45 degrees so it intersects with the ground. 3. Give the mesh light plane an emission shader and render it in Cycles.

Weird Mesh Light Sampling.blend

921 KiB

Example sampling pattern.png

550 KiB

Alaska added the

labels 2023-09-27 02:50:01 +02:00

Richard Antalik commented

2023-09-27 04:03:42 +02:00

Member

Can confirm, broken between 0a004fbad4 and ab6860f3de

Can confirm, broken between 0a004fbad460 and ab6860f3de0f

Richard Antalik changed title from ~~Regression: Cycles: Weird Mesh Light Sampling~~ to Regression: Cycles: Weird Mesh Light Sampling

2023-09-27 04:03:51 +02:00

Richard Antalik added

Render & Cycles

and removed

labels 2023-09-27 04:04:11 +02:00

Iliya Katushenock added

Render & Cycles

and removed

Render & Cycles

labels 2023-09-27 07:31:46 +02:00

Philipp Oeser commented

2023-09-27 10:33:52 +02:00

Member

Suspect is 97d9bbbc97 , will double-check

Suspect is 97d9bbbc97f85e4d309c843a063a73123265e317 , will double-check

Philipp Oeser commented

2023-09-27 10:52:05 +02:00

Member

@weizhen : could you check?

@weizhen : could you check?

Brecht Van Lommel commented

2023-09-27 13:43:19 +02:00

Owner

@lichtwerk Weizhen is away for the next 6 months, so I will handle this bug.

@lichtwerk Weizhen is away for the next 6 months, so I will handle this bug.

Steffen Dünner commented

2023-09-27 14:50:32 +02:00

This might not be the most exciting news to you but it renders properly when setting Emission Sampling of the emitting grid to "none".

This might not be the most exciting news to you but it renders properly when setting Emission Sampling of the emitting grid to "none". ![image](/attachments/63129fd1-ad46-405c-b753-6a11cc31b873) ![image](/attachments/5cbf20bf-0714-406a-8ae3-01365115a476)

1.6 MiB

7.8 KiB

Brecht Van Lommel commented

2023-09-29 20:19:21 +02:00

Owner

Yes, it's expected because that option disables the code that was changed in 97d9bbbc97.

Yes, it's expected because that option disables the code that was changed in 97d9bbbc97f85e4d309c843a063a73123265e317.

Brecht Van Lommel referenced this issue from a commit

2023-10-02 19:21:20 +02:00

Fix #112931: Cycles mesh light sampling artifacts

Brecht Van Lommel closed this issue

2023-10-02 19:23:30 +02:00

Blender Bot added

and removed

labels 2023-10-02 19:23:31 +02:00

Joseph Eagar referenced this issue from a commit

2023-10-07 21:46:17 +02:00

Fix #112931: Cycles mesh light sampling artifacts

Joseph Eagar referenced this issue from a commit

2023-10-07 21:46:18 +02:00

Fix #112931: Cycles mesh light sampling artifacts

Brecht Van Lommel referenced this issue from a commit

2023-11-06 19:08:46 +01:00

Fix #112931: Cycles mesh light sampling artifacts

Brecht Van Lommel referenced this issue

2023-11-06 19:11:32 +01:00

Blender LTS: Maintenance Task 3.6 #109399

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