Light Groups World Environment anomaly #103507

Closed
opened 2022-12-28 03:40:13 +01:00 by Mark Stead · 6 comments

System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 527.56

Blender Version
Broken: version: 3.4.0, branch: blender-v3.4-release, commit date: 2022-12-06 18:46, hash: a95bf1ac01
Worked: None
I got the same result in versions 3.3.2 and 3.2.2.

Short description of error
I'm adding Light Groups to an existing scene, and found that when adding the Lights Groups together the brightness of the image did not match the normal composite.
I've created and attached a sample scene below where changing a Multiple Importance on a Light setting affects the Light Group for the world environment.

Exact steps for others to reproduce the error

  • Starting with default scene, I've changed the Render Engine to Cycles, and selected GPU Compute, reduced samples and turned off denoising.
  • In the View Layer Properties, I've created two Lights Groups Env and Light.
  • In the World Properties, I've assigned the Light Group Env and set the Color to black (0, 0, 0) and Strength to 0.
  • For the Light object, I've changed to type to Sun, set the Strength to 1, the Angle to 90 degrees and the Light Group to Light.
  • In Compositing, I've added Viewer nodes for the Image, Combined_Env and Combined_Light outputs.

Render, and check the Viewer nodes. The Combined_Env should be black, but is not - it is kind of a much dimmer version of the Combined_Light.
Light Groups and Environment problem.blend
image.png

Modify the Light and turn off Multiple Importance. Render again, and now Combined_Env is black.
image.png

Reducing the Light angle lessens the effect. Turn on Multiple Importance again, and set the Angle to 10 degrees.
The Combined_Env appears black.
image.png

However, add an Exposure node (Strength 10) and you can see it is not black.
image.png

I know this is a really weird (contrived) example. In my real scene I was rendering stars on a black background for the environment but using IsCameraRay to disable illumination. Then I had a separate sky dome light which was a Sun light with a very wide angle. When I started using Light Groups there was a significant difference in the lighting.

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 527.56 **Blender Version** Broken: version: 3.4.0, branch: blender-v3.4-release, commit date: 2022-12-06 18:46, hash: `a95bf1ac01` Worked: None I got the same result in versions 3.3.2 and 3.2.2. **Short description of error** I'm adding Light Groups to an existing scene, and found that when adding the Lights Groups together the brightness of the image did not match the normal composite. I've created and attached a sample scene below where changing a Multiple Importance on a Light setting affects the Light Group for the world environment. **Exact steps for others to reproduce the error** - Starting with default scene, I've changed the Render Engine to Cycles, and selected GPU Compute, reduced samples and turned off denoising. - In the View Layer Properties, I've created two Lights Groups Env and Light. - In the World Properties, I've assigned the Light Group Env and set the Color to black (0, 0, 0) and Strength to 0. - For the Light object, I've changed to type to Sun, set the Strength to 1, the Angle to 90 degrees and the Light Group to Light. - In Compositing, I've added Viewer nodes for the Image, Combined_Env and Combined_Light outputs. Render, and check the Viewer nodes. The Combined_Env should be black, but is not - it is kind of a much dimmer version of the Combined_Light. [Light Groups and Environment problem.blend](https://archive.blender.org/developer/F14096282/Light_Groups_and_Environment_problem.blend) ![image.png](https://archive.blender.org/developer/F14096291/image.png) Modify the Light and turn off Multiple Importance. Render again, and now Combined_Env is black. ![image.png](https://archive.blender.org/developer/F14096293/image.png) Reducing the Light angle lessens the effect. Turn on Multiple Importance again, and set the Angle to 10 degrees. The Combined_Env appears black. ![image.png](https://archive.blender.org/developer/F14096300/image.png) However, add an Exposure node (Strength 10) and you can see it is not black. ![image.png](https://archive.blender.org/developer/F14096304/image.png) I know this is a really weird (contrived) example. In my real scene I was rendering stars on a black background for the environment but using IsCameraRay to disable illumination. Then I had a separate sky dome light which was a Sun light with a very wide angle. When I started using Light Groups there was a significant difference in the lighting.
Author

Added subscriber: @MarkStead-2

Added subscriber: @MarkStead-2
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Changed status from 'Needs Triage' to: 'Confirmed'

Changed status from 'Needs Triage' to: 'Confirmed'
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Added subscribers: @PratikPB2123, @LukasStockner

Added subscribers: @PratikPB2123, @LukasStockner
Lukas Stockner self-assigned this 2023-01-06 00:40:37 +01:00

This issue was referenced by faca2c614b

This issue was referenced by faca2c614b67a1b66e55ad20df5eb30cb009a757

This issue was referenced by bc5337a05a

This issue was referenced by bc5337a05a22518051f71f26ac1948e327c2ebd9
Member

Changed status from 'Confirmed' to: 'Resolved'

Changed status from 'Confirmed' to: 'Resolved'
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Reference: blender/blender#103507
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