GPU volume glitch with an emissive plane and camera/view inside volume object #82902

New Issue

Nuuti · 2020-11-21T14:53:13+01:00

Nuuti commented

2020-11-21 14:53:13 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce RTX 2060 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71

Blender Version
Broken: version: 2.83.0, branch: master, commit date: 2020-06-03 14:38, hash: 211b6c29f7
Worked: (newest version of Blender that worked as expected)

Short description of error
As you open the blend file and go into rendered view the back plane that has emissive properites will clip trough rest of the mesh. It's nothing major luckily, just a visual bug

Exact steps for others to reproduce the error
Station_39.blend
Open the attached blend file, DO NOT move the world view. Go in to rendered view on the right window.

The Material.013 material on Neon_kyltit in combination with Material.003 on Tausta_blue seem to cause the glitches (for me)

Glitch looks like this btw and only appear on GPU.:

This is on CPU

Material.013 is not even assigned to any faces.
If any of the two get removed, all is good again.

Checked a bit more and here is a simplified file:
Volume_emission_glitch.blend

camera/view being inside an object with a material that has an emission plugged into the volume slot
looking at an object/face that also needs to meet "weird" requirements:
- has an emission shader in the material volume slot
- has normals pointing in both directions

Looks like this then:

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce RTX 2060 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71 **Blender Version** Broken: version: 2.83.0, branch: master, commit date: 2020-06-03 14:38, hash: `211b6c29f7` Worked: (newest version of Blender that worked as expected) **Short description of error** As you open the blend file and go into rendered view the back plane that has emissive properites will clip trough rest of the mesh. It's nothing major luckily, just a visual bug **Exact steps for others to reproduce the error** [Station_39.blend](https://archive.blender.org/developer/F9347938/Station_39.blend) Open the attached blend file, DO NOT move the world view. Go in to rendered view on the right window. The `Material.013` material on `Neon_kyltit` in combination with `Material.003` on `Tausta_blue` seem to cause the glitches (for me) Glitch looks like this btw and only appear on GPU.: ![image.png](https://archive.blender.org/developer/F9372591/image.png) This is on CPU ![image.png](https://archive.blender.org/developer/F9372578/image.png) `Material.013` is not even assigned to any faces. If any of the two get removed, all is good again. Checked a bit more and here is a simplified file: [Volume_emission_glitch.blend](https://archive.blender.org/developer/F9372722/Volume_emission_glitch.blend) - camera/view being inside an object with a material that has an emission plugged into the volume slot - looking at an object/face that also needs to meet "weird" requirements: - has an emission shader in the material volume slot - has normals pointing in both directions ![image.png](https://archive.blender.org/developer/F9372783/image.png) Looks like this then: ![image.png](https://archive.blender.org/developer/F9372749/image.png)

Nuuti commented

2020-11-21 14:53:13 +01:00

Added subscriber: @Nuudom

Nuuti commented

2020-11-21 14:54:55 +01:00

Not that in depth with the inner workings of blender, but came accross this visual bug

Alaska commented

2020-11-21 19:30:35 +01:00

Added subscriber: @Alaska

Alaska commented

2020-11-21 19:30:35 +01:00

The issue seems to be caused by the emission shader plugged into the volume output on the plane that shows the visual glitches. Unplugging the emission shader seems to fix this issue.

As for why the emission shader is causing issues, it seems to have something to do with the fact the plane is a backface on both sides, causing the "outside" to be the volume in which the volume shader takes effect? However, that doesn't explain why it only effects a certain area of the scene.

The issue seems to be caused by the emission shader plugged into the volume output on the plane that shows the visual glitches. Unplugging the emission shader seems to fix this issue. As for why the emission shader is causing issues, it seems to have something to do with the fact the plane is a backface on both sides, causing the "outside" to be the volume in which the volume shader takes effect? However, that doesn't explain why it only effects a certain area of the scene.

Germano Cavalcante commented

2020-11-24 15:09:42 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-11-24 15:09:42 +01:00

I'm not sure I can identify the problem:

I'm not sure I can identify the problem: ![image.png](https://archive.blender.org/developer/F9365669/image.png)

Philipp Oeser commented

2020-11-25 15:07:24 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-11-25 15:07:24 +01:00

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

Philipp Oeser commented

2020-11-25 15:07:24 +01:00

The Material.013 material on Neon_kyltit in combination with Material.003 on Tausta_blue seem to cause the glitches (for me)

They look like this btw and only appear on GPU.:

This is on CPU

Material.013 is not even assigned to any faces.
If any of the two get removed, all is good again.

Checked a bit more and here is a simplified file:
Volume_emission_glitch.blend

camera/view being inside an object with a material that has an emission plugged into the volume slot
looking at an object/face that also needs to meet "weird" requirements:
- has an emission shader in the material volume slot
- has normals pointing in both directions (@Alaska: do you know how to even get these?)

Looks like this then:

Will confirm for now (even though this looks like a real corner-case?)

The `Material.013` material on `Neon_kyltit` in combination with `Material.003` on `Tausta_blue` seem to cause the glitches (for me) They look like this btw and only appear on GPU.: ![image.png](https://archive.blender.org/developer/F9372591/image.png) This is on CPU ![image.png](https://archive.blender.org/developer/F9372578/image.png) `Material.013` is not even assigned to any faces. If any of the two get removed, all is good again. Checked a bit more and here is a simplified file: [Volume_emission_glitch.blend](https://archive.blender.org/developer/F9372722/Volume_emission_glitch.blend) - camera/view being inside an object with a material that has an emission plugged into the volume slot - looking at an object/face that also needs to meet "weird" requirements: - has an emission shader in the material volume slot - has normals pointing in both directions (@Alaska: do you know how to even get these?) ![image.png](https://archive.blender.org/developer/F9372783/image.png) Looks like this then: ![image.png](https://archive.blender.org/developer/F9372749/image.png) Will confirm for now (even though this looks like a real corner-case?)

Philipp Oeser changed title from ~~A visual bug with an emissive plane and rendered view~~ to GPU volume glitch with an emissive plane and camera/view inside volume object

2020-11-25 15:10:49 +01:00

Alaska commented

2020-11-28 23:39:30 +01:00

In #82902#1061073, @lichtwerk wrote:
...
-- has normals pointing in both directions (@Alaska: do you know how to even get these?)

I have absolutely no idea how to reproduce this. I played around a bit and have personally been unable to reproduce this. Maybe @Nuudom can shed some light on this?

> In #82902#1061073, @lichtwerk wrote: > ... > -- has normals pointing in both directions (@Alaska: do you know how to even get these?) > > ![image.png](https://archive.blender.org/developer/F9372783/image.png) > I have absolutely no idea how to reproduce this. I played around a bit and have personally been unable to reproduce this. Maybe @Nuudom can shed some light on this?

Nuuti commented

2020-11-29 06:16:16 +01:00

I actually have no idea how I managed that 😅 i didn't know why the plane was connected to an volume output to begin with to be honest.

All I can guess at with my tiny knowleage is that I may have made too many clicks and key shortcuts at the same time and it just bugged out.

Maybe someone familiar with code could view the project data if that file has any.

I actually have no idea how I managed that 😅 i didn't know why the plane was connected to an volume output to begin with to be honest. All I can guess at with my tiny knowleage is that I may have made too many clicks and key shortcuts at the same time and it just bugged out. Maybe someone familiar with code could view the project data if that file has any.

Brecht Van Lommel commented

2021-11-05 23:11:29 +01:00

Added subscriber: @brecht

Brecht Van Lommel commented

2021-11-05 23:11:29 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Brecht Van Lommel closed this issue

2021-11-05 23:11:29 +01:00

Brecht Van Lommel self-assigned this 2021-11-05 23:11:29 +01:00

Brecht Van Lommel commented

2021-11-05 23:11:29 +01:00

Blender 3.0 is giving consistent results for CPU and GPU here. Beyond that the mesh does not appear to be closed, which is required for volume rendering to work correctly.

Sign in to join this conversation.

No Label

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

GPU volume glitch with an emissive plane and camera/view inside volume object #82902