Eevee: Specular Light: The sepecular light contribution should be limited to samples with a normal pointing toward the camera #81070

New Issue

Michael Möller · 2020-09-23T00:25:37+02:00

Michael Möller commented

2020-09-23 00:25:37 +02:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2070 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.38

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-22 18:36, hash: 358a8e00bd
Worked: Unknown

Short description of error
Eevee produces render artifacts on the specular light contribution when the normal vector points away from the camera (for example because of active smooth shading). This can be seen as bright (wrong) reflections near the visibility boundary of the geometry. Cycles does not produce these artifacts, there seems to be no specular light contribution on normals facing away from the camera.

Eevee (wrong specular reflection on the left):

Cycles (correct specular reflections):

Exact steps for others to reproduce the error
Load the attached .blend file and render the image with Eeevee (and to compare) with Cycles. To better understand the problem a dark red color has been added (as Emission) to the parts of the geometry with normals pointing away from the camera, and dark green for parts with normals pointing towards the camera. The specular reflections are white. The .blend file also contains a node group "View Clamped Normal" that allows to "correct" the normals (by changing them so they are not pointing away from the camera). This can be connected to the "Normal" input of the BSDF to hide the problem, as a workaround.

eevee-specular.blend

Suggested fix
Attached is a patch file for a suggested fix in blender/draw/engines/eevee/shaders/lights_lib.glsl by adding the check if dot(N, V) > 0.0 before calculating the specular contribution and returning 0.0 otherwise.

0001-Correct-the-specular-light-contribution.patch

Eevee (with the attached patch applied)

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce RTX 2070 SUPER/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.38 **Blender Version** Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-22 18:36, hash: `358a8e00bd` Worked: Unknown **Short description of error** Eevee produces render artifacts on the specular light contribution when the normal vector points away from the camera (for example because of active smooth shading). This can be seen as bright (wrong) reflections near the visibility boundary of the geometry. Cycles does not produce these artifacts, there seems to be no specular light contribution on normals facing away from the camera. Eevee (wrong specular reflection on the left): ![Eevee.png](https://archive.blender.org/developer/F8910260/Eevee.png) Cycles (correct specular reflections): ![Cycles.png](https://archive.blender.org/developer/F8910263/Cycles.png) **Exact steps for others to reproduce the error** Load the attached .blend file and render the image with Eeevee (and to compare) with Cycles. To better understand the problem a dark red color has been added (as Emission) to the parts of the geometry with normals pointing away from the camera, and dark green for parts with normals pointing towards the camera. The specular reflections are white. The .blend file also contains a node group "View Clamped Normal" that allows to "correct" the normals (by changing them so they are not pointing away from the camera). This can be connected to the "Normal" input of the BSDF to hide the problem, as a workaround. [eevee-specular.blend](https://archive.blender.org/developer/F8910317/eevee-specular.blend) **Suggested fix** Attached is a patch file for a suggested fix in blender/draw/engines/eevee/shaders/lights_lib.glsl by adding the check if dot(N, V) > 0.0 before calculating the specular contribution and returning 0.0 otherwise. [0001-Correct-the-specular-light-contribution.patch](https://archive.blender.org/developer/F8910318/0001-Correct-the-specular-light-contribution.patch) Eevee (with the attached patch applied) ![Eeeve-Patched.png](https://archive.blender.org/developer/F8910310/Eeeve-Patched.png)

Michael Möller commented

2020-09-23 00:25:37 +02:00

Added subscriber: @mmoeller

blender-admin commented

2020-09-23 00:25:37 +02:00

#85393 was marked as duplicate of this issue

Bent Hillerkus commented

2020-09-23 02:32:02 +02:00

Added subscriber: @bent

Michael Möller commented

2020-09-23 19:16:46 +02:00

The above image and .blend file is rather synthetic to make the problem visible. A more typical case is shown in the following image:

The bright pixels on the upper left limit of the sphere should not be there. The image can be reproduced with the attached .blend file:

specular-artifact.blend

The .blend file contains a (smooth shaded) icosphere with a principled BSDF shader. Also for this case, the issue is not visible when rendered with Cycles.

The above image and .blend file is rather synthetic to make the problem visible. A more typical case is shown in the following image: ![specular-artifact.png](https://archive.blender.org/developer/F8912550/specular-artifact.png) The bright pixels on the upper left limit of the sphere should not be there. The image can be reproduced with the attached .blend file: [specular-artifact.blend](https://archive.blender.org/developer/F8912555/specular-artifact.blend) The .blend file contains a (smooth shaded) icosphere with a principled BSDF shader. Also for this case, the issue is not visible when rendered with Cycles.

Germano Cavalcante commented

2020-09-25 21:18:30 +02:00

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

Germano Cavalcante commented

2021-02-09 19:31:24 +01:00

Added subscriber: @YAFU

blender-admin commented

2021-03-03 13:14:24 +01:00

This issue was referenced by 1c22b551d0

This issue was referenced by 1c22b551d0c13ad90bdc6145e6fa7db763038523

Clément Foucault commented

2021-03-03 15:22:50 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Clément Foucault closed this issue

2021-03-03 15:22:50 +01:00

Clément Foucault self-assigned this 2021-03-03 15:22:50 +01:00

YAFU commented

2021-03-23 23:45:02 +01:00

@fclem , Thanks for the fix, it solves most of the problem. Just to mention just in case, that even with the fix in certain circumstances (it may depend on the amount of geometry of the mesh and the angle of the view) small fireflies/artifacts may still appear at the edges. For example here (it is more noticeable in the final render image)
Eevee_Specular.blend

EDIT:
Now I'm not sure if this is the same problem or if I should open a new report. The fireflies problem occurs even without lamps and without World lighting, when the material has a Principled BSDF shader:
Eevee_Principled BSDF_fireflies.blend

EDIT 2:
Film > Filter Size value changes number of fireflies.

EDIT 3:
Fixed on master, thanks.

@fclem , Thanks for the fix, it solves most of the problem. Just to mention just in case, that even with the fix in certain circumstances (it may depend on the amount of geometry of the mesh and the angle of the view) small fireflies/artifacts may still appear at the edges. For example here (it is more noticeable in the final render image) [Eevee_Specular.blend](https://archive.blender.org/developer/F9906147/Eevee_Specular.blend) EDIT: Now I'm not sure if this is the same problem or if I should open a new report. The fireflies problem occurs even without lamps and without World lighting, when the material has a Principled BSDF shader: [Eevee_Principled BSDF_fireflies.blend](https://archive.blender.org/developer/F9906949/Eevee_Principled_BSDF_fireflies.blend) EDIT 2: Film > Filter Size value changes number of fireflies. EDIT 3: Fixed on master, thanks.

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

Eevee: Specular Light: The sepecular light contribution should be limited to samples with a normal pointing toward the camera #81070