HIP-RT transparent shadows rendering artifacts #117527

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opened 2024-01-26 01:44:32 +01:00 by Alaska · 8 comments

Alaska commented

2024-01-26 01:44:32 +01:00

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System Information
Operating system: Windows-10-10.0.22621-SP0 64 Bits
Graphics card: AMD Radeon RX 7800 XT ATI Technologies Inc. 4.6.0 Core Profile Context 24.1.1.240110

Blender Version
Broken: version: 4.0.2, branch: blender-v4.0-release, commit date: 2023-12-05 07:41, hash: 9be62e85b727
Worked: NA

Short description of error
When using HIP-RT, the shadows of objects that make use of a transparent BSDF will render with artifacts. And these artifacts can appear and disappear based on the number of faces the object has and how large the object is, as demonstrated in the video below:

HIP	HIP-RT

Exact steps for others to reproduce the error

Open the attached .blend file.
Render it on a AMD GPU with HIP-RT.
Compare it to other options (E.G. HIP, CPU rendering, other rendering backends on other GPUs, etc)

**System Information** Operating system: Windows-10-10.0.22621-SP0 64 Bits Graphics card: AMD Radeon RX 7800 XT ATI Technologies Inc. 4.6.0 Core Profile Context 24.1.1.240110 **Blender Version** Broken: version: 4.0.2, branch: blender-v4.0-release, commit date: 2023-12-05 07:41, hash: `9be62e85b727` Worked: NA **Short description of error** When using HIP-RT, the shadows of objects that make use of a transparent BSDF will render with artifacts. And these artifacts can appear and disappear based on the number of faces the object has and how large the object is, as demonstrated in the video below: |HIP|HIP-RT| |-|-| |![HIP.jpg](/attachments/f5797880-5b02-46a0-a9ca-dc967d86d9f0)|![HIP-RT.jpg](/attachments/02711d06-a6f8-4e6d-81d7-b57bae15967f)| <video src="/attachments/aeea02b0-2ed8-4505-b5a6-8122234d6b9e" title="HIP-RT Transparency Artifacts Demonstration Video.mp4" controls></video> **Exact steps for others to reproduce the error** 1. Open the attached .blend file. 2. Render it on a AMD GPU with HIP-RT. 3. Compare it to other options (E.G. HIP, CPU rendering, other rendering backends on other GPUs, etc)

HIP-RT Transparency Artifacts Demonstration Video.mp4

4.0 MiB

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HIP-RT Transparency Artifacts.blend

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Alaska added the

labels 2024-01-26 01:44:33 +01:00

Alaska referenced this issue

2024-01-27 02:52:15 +01:00

HIP-RT will not be automatically used in certain situations with Persistent Data #117566

Alaska changed title from ~~HIP-RT transparent rendering artifacts~~ to HIP-RT transparent shadows rendering artifacts

2024-01-27 04:57:07 +01:00

Philipp Oeser commented

2024-03-27 11:22:15 +01:00

Member

@Jeroen-Bakker @brecht : are you able to verify this?

@Jeroen-Bakker @brecht : are you able to verify this?

Philipp Oeser added the

Render & Cycles

label 2024-03-27 11:22:45 +01:00

Brecht Van Lommel commented

2024-03-27 17:14:26 +01:00

Owner

@salipour can you check this?

@salipour can you check this?

Sahar A. Kashi commented

2024-03-29 00:59:45 +01:00

Member

This has to do with our AS spatial splitting. Hopefully, we'll have a fix by the next release. A workaround for now could be disabling spatial split (but I don't really recommend it). The other workaround could be disabling spatial splitting only for transparent objects, but I am not sure about performance implications without trying various scenes. Is it a common issue with regular scenes?

This has to do with our AS spatial splitting. Hopefully, we'll have a fix by the next release. A workaround for now could be disabling spatial split (but I don't really recommend it). The other workaround could be disabling spatial splitting only for transparent objects, but I am not sure about performance implications without trying various scenes. Is it a common issue with regular scenes?

Alaska commented

2024-03-29 01:15:02 +01:00

Author

Member

Is it a common issue with regular scenes?

In architectural rendering, I would say yes, this is a semi-common issue. This is because the issue is present in the shadow of glass windows that makes use of the architectural glass shader setup below. As for other scenes, I think this issue is significantly less common.

As you've probably already noticed, setting the transparent BSDF colour to 1,1,1 white makes it fully transparent and there are no visible artefacts. So in most scenes that do make use of transparency in a "normal way" (E.G. Scenes with vegetation where the leaves are cards with alpha masks), this is a non-issue.

> Is it a common issue with regular scenes? In architectural rendering, I would say yes, this is a semi-common issue. This is because the issue is present in the shadow of glass windows that makes use of the architectural glass shader setup below. As for other scenes, I think this issue is significantly less common. As you've probably already noticed, setting the transparent BSDF colour to 1,1,1 white makes it fully transparent and there are no visible artefacts. So in most scenes that do make use of transparency in a "normal way" (E.G. Scenes with vegetation where the leaves are cards with alpha masks), this is a non-issue. ![Screenshot 2024-03-29 at 13.10.27.png](/attachments/9cb0e3ec-866b-45f3-b46b-6e83e5842ff5)

Screenshot 2024-03-29 at 13.10.27.png

309 KiB

Alaska added

and removed

labels 2024-03-29 02:01:08 +01:00

Alaska commented

2024-03-29 02:48:53 +01:00

Author

Member

Hopefully, we'll have a fix by the next release.

Just confirming, the next release of the HIP-RT SDK?
If the fix is in HIP-RT, is there a time frame for when the next version of the HIP-RT SDK is expected to release.

> Hopefully, we'll have a fix by the next release. Just confirming, the next release of the HIP-RT SDK? If the fix is in HIP-RT, is there a time frame for when the next version of the HIP-RT SDK is expected to release.

Sahar A. Kashi commented

2024-03-29 17:46:04 +01:00

Member

I meant the next release of HIP-RT SDK and I expect that to happen before the next release of Blender.

I meant the next release of HIP-RT SDK and I expect that to happen before the next release of Blender.

Philipp Oeser added

Render & Cycles

and removed

Render & Cycles

labels 2024-04-02 11:03:15 +02:00

Sahar A. Kashi commented

2024-04-15 19:10:05 +02:00

Member

@Alaska can you share more complicated scenes that reproduce the issue?

@Alaska can you share more complicated scenes that reproduce the issue?

Alaska commented

2024-04-16 05:44:22 +02:00

Author

Member

@salipour I rarely use my AMD GPU for Cycles rendering, so I've only encountered this issue in one complex scene. A house render where the issue occurred in the window shadows (The test file I uploaded in the original report is just two windows from that scene).

I have uploaded a simplified version of that house scene for you to test with.
By "simplified", I mean I removed a lot of materials/textures to reduce the file size. And removed some assets I do not have permission to share (Two cars, and vegetation I had scattered across the landscape).
Simplified house scene.blend

This scene was created by exporting a 3D model from a Architectural CAD software, then making minor modifications to fix some geometry issues, then I did some material and lighting work and added a mountainous backdrop.

BVH2	HIP-RT BVH

@salipour I rarely use my AMD GPU for Cycles rendering, so I've only encountered this issue in one complex scene. A house render where the issue occurred in the window shadows (The test file I uploaded in the original report is just two windows from that scene). I have uploaded a simplified version of that house scene for you to test with. By "simplified", I mean I removed a lot of materials/textures to reduce the file size. And removed some assets I do not have permission to share (Two cars, and vegetation I had scattered across the landscape). [Simplified house scene.blend](/attachments/20a433a2-2d80-4318-aee7-1eb61bbc4e71) This scene was created by exporting a 3D model from a Architectural CAD software, then making minor modifications to fix some geometry issues, then I did some material and lighting work and added a mountainous backdrop. |BVH2|HIP-RT BVH| |-|-| |![BVH2.jpg](/attachments/af86bd60-87a7-4f45-a5f1-7368acbacfae)|![HIP-RT.jpg](/attachments/798391e5-3b6c-416b-a772-e13a61a773ac)|

Simplified house scene.blend

15 MiB

158 KiB

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