Cycles cryptomatte is noisy around materials with fully transparent shader #102381

New Issue

Louis Florentin · 2022-11-09T15:13:00+01:00

Louis Florentin commented

2022-11-09 15:13:00 +01:00

System Information
Operating system: Windows 11, x64
Graphics card: NVIDIA Quadro RTX 4000

Blender Version
Broken: 3.5.0 Alpha

Worked: None

Short description of error
Two problems can be observed in the compositor (cf. attached .blend file):

the matte from the cryptomatte node (monkey + glasses) is slightly inferior to 1 around the lenses of the glasses (transparent material) even where the monkey is behind the lenses. This matte should be the same as the alpha channel from the "foreground" view layer.
when setting the collection with all the objects (monkey + glasses) to holdout in the "background" view layer, the lenses (not the whole glasses) still appear on the matte from the cryptomatte node and connected to the same "background" view layer whereas it shouldn't (as the collection is holdout from the "background" view layer).

Exact steps for others to reproduce the error

Open attached .blend file SEGM_MASK_Blender_bug_v2.blend
Open the compositing workspace
F12 to render (using Cycles)
See the differences between the alpha channel coming from the "foreground" view layer and the matte from the cryptomatte node and connected to the same "foreground" view layer.
See that (only) the lenses of the glasses still appear on the matte from the cryptomatte node and connected to the "background" view layer whereas it shouldn't as the whole collection of objects is holdout from the same "background" layer.

**System Information** Operating system: Windows 11, x64 Graphics card: NVIDIA Quadro RTX 4000 **Blender Version** Broken: 3.5.0 Alpha ![image.png](https://archive.blender.org/developer/F13875560/image.png) Worked: None **Short description of error** Two problems can be observed in the compositor (cf. attached .blend file): 1) the matte from the cryptomatte node (monkey + glasses) is slightly inferior to 1 around the lenses of the glasses (transparent material) even where the monkey is behind the lenses. This matte should be the same as the alpha channel from the "foreground" view layer. 2) when setting the collection with all the objects (monkey + glasses) to holdout in the "background" view layer, the lenses (not the whole glasses) still appear on the matte from the cryptomatte node and connected to the same "background" view layer whereas it shouldn't (as the collection is holdout from the "background" view layer). **Exact steps for others to reproduce the error** - Open attached .blend file [SEGM_MASK_Blender_bug_v2.blend](https://archive.blender.org/developer/F13955961/SEGM_MASK_Blender_bug_v2.blend) - Open the compositing workspace ![image.png](https://archive.blender.org/developer/F13875808/image.png) ![image.png](https://archive.blender.org/developer/F13875800/image.png) - F12 to render (using Cycles) - See the differences between the alpha channel coming from the "foreground" view layer and the matte from the cryptomatte node and connected to the same "foreground" view layer. ![image.png](https://archive.blender.org/developer/F13875717/image.png) - See that (only) the lenses of the glasses still appear on the matte from the cryptomatte node and connected to the "background" view layer whereas it shouldn't as the whole collection of objects is holdout from the same "background" layer. ![image.png](https://archive.blender.org/developer/F13875727/image.png)

Louis Florentin commented

2022-11-09 15:13:00 +01:00

Added subscriber: @louis_de_florence

Omar Emara commented

2022-11-21 12:47:57 +01:00

Added subscriber: @OmarEmaraDev

Omar Emara commented

2022-11-21 12:47:57 +01:00

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

Omar Emara commented

2022-11-21 12:47:57 +01:00

It seems this file doesn't include the monkey in your screenshots, and doesn't have the exact same composite node tree. Is this intended?
Can you try to simplify the file to only contain simple objects with no environment textures or other non significant resources? And also, provide steps that demonstrate how you constructed the file?

It seems this file doesn't include the monkey in your screenshots, and doesn't have the exact same composite node tree. Is this intended? Can you try to simplify the file to only contain simple objects with no environment textures or other non significant resources? And also, provide steps that demonstrate how you constructed the file?

Omar Emara was assigned by Louis Florentin

2022-11-21 13:16:21 +01:00

Louis Florentin commented

2022-11-21 13:16:21 +01:00

In #102381#1449011, @OmarEmaraDev wrote:
It seems this file doesn't include the monkey in your screenshots, and doesn't have the exact same composite node tree. Is this intended?
Can you try to simplify the file to only contain simple objects with no environment textures or other non significant resources? And also, provide steps that demonstrate how you constructed the file?

Hey Omar, thanks a lot for your response!
I updated the simplified blend scene, let me know if there is still an issue.
Steps to create the scene:

Add glasses
Add monkey
Add lights
Create a collection "Collection" and add all objects to it
Rename the current view layer to "Background"
Create a second view layer named "Foreground'
Go to the "Background" view layer and set the collection "Collection" to holdout (right click on the collection in the outliner view and View Layer > Set Holdout) : it should hide all the objects from the collection in the "Background" view layer

I hope it makes sense. Let me know if you need additional information.
Thanks a lot!

> In #102381#1449011, @OmarEmaraDev wrote: > It seems this file doesn't include the monkey in your screenshots, and doesn't have the exact same composite node tree. Is this intended? > Can you try to simplify the file to only contain simple objects with no environment textures or other non significant resources? And also, provide steps that demonstrate how you constructed the file? Hey Omar, thanks a lot for your response! I updated the simplified blend scene, let me know if there is still an issue. Steps to create the scene: - Add glasses - Add monkey - Add lights - Create a collection "Collection" and add all objects to it - Rename the current view layer to "Background" - Create a second view layer named "Foreground' - Go to the "Background" view layer and set the collection "Collection" to holdout (right click on the collection in the outliner view and View Layer > Set Holdout) : it should hide all the objects from the collection in the "Background" view layer I hope it makes sense. Let me know if you need additional information. Thanks a lot!

Omar Emara commented

2022-11-21 13:16:46 +01:00

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

Omar Emara commented

2022-11-21 13:17:18 +01:00

Thanks for the update, I will take a look.

Omar Emara removed their assignment 2022-11-21 13:17:38 +01:00

Omar Emara commented

2022-12-06 10:23:15 +01:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Omar Emara commented

2022-12-06 10:23:15 +01:00

Added subscriber: @brecht

Omar Emara commented

2022-12-06 10:23:15 +01:00

The values around the glasses seems expected because your shader is a mix between a fully transparent shader and a glass one, fully transparent objects seems to be absent from cryptomatte producing a black matte, so they lower the values of the matte a bit after convergence.

@brecht Given two planes, the top of which has the shader shown below, and a compositor setup that generates the matte from both planes, is it expected to get edges that are slightly less than 1?

The values around the glasses seems expected because your shader is a mix between a fully transparent shader and a glass one, fully transparent objects seems to be absent from cryptomatte producing a black matte, so they lower the values of the matte a bit after convergence. @brecht Given two planes, the top of which has the shader shown below, and a compositor setup that generates the matte from both planes, is it expected to get edges that are slightly less than 1? ![20221206-111551.png](https://archive.blender.org/developer/F14000420/20221206-111551.png)

Omar Emara changed title from ~~Bug: matte from cryptomatte node incorrect around transparent material~~ to Cycles cryptomatte is noisy around materials with fully transparent shader

2022-12-06 10:24:06 +01:00

Philipp Oeser removed the

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Cycles cryptomatte is noisy around materials with fully transparent shader #102381