EEVEE lighsource reflections bug or feature? (shadows being used for visibility could be documented) #89556

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opened 2021-06-30 14:45:54 +02:00 by Dan Pastean · 9 comments

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: Quadro K4000/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 462.59

Blender Version
Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-06-24 17:40, hash: blender/blender@3d7021b4ec
Worked: (doesnt work even in 2.83 LTS)

Short description of error
From the attached images and file there seems to be an issue where reflections dont show up when a light is present, while using an emission surface gives the expected result. Please note that using reflection planes, cube mapps do nothing to the scene, it seems that EEVEE overlays lights reflections on top of everything, except surface roughness. I`m not sure if its a bug or a feature.

Exact steps for others to reproduce the error
Please see attached file
White room bug.blend

Evee lights_no reflection.png
Eevee emission material_reflections ok.png

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: Quadro K4000/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 462.59 **Blender Version** Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-06-24 17:40, hash: `blender/blender@3d7021b4ec` Worked: (doesnt work even in 2.83 LTS) **Short description of error** From the attached images and file there seems to be an issue where reflections dont show up when a light is present, while using an emission surface gives the expected result. Please note that using reflection planes, cube mapps do nothing to the scene, it seems that EEVEE overlays lights reflections on top of everything, except surface roughness. I`m not sure if its a bug or a feature. **Exact steps for others to reproduce the error** Please see attached file [White room bug.blend](https://archive.blender.org/developer/F10206594/White_room_bug.blend) ![Evee lights_no reflection.png](https://archive.blender.org/developer/F10206598/Evee_lights_no_reflection.png) ![Eevee emission material_reflections ok.png](https://archive.blender.org/developer/F10206601/Eevee_emission_material_reflections_ok.png)
Author

Added subscriber: @Pastean_Narcis_Dan

Added subscriber: @Pastean_Narcis_Dan
Author
[White room bug.blend](https://archive.blender.org/developer/F10206603/White_room_bug.blend)

Added subscriber: @ktdfly

Added subscriber: @ktdfly

AFAIK that's a limitation of LTC shading - specular highlights are only checked if in direct shadow, reflected rays are not checked

AFAIK that's a limitation of LTC shading - specular highlights are only checked if in direct shadow, reflected rays are not checked
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Added subscribers: @fclem, @lichtwerk

Added subscribers: @fclem, @lichtwerk
Member

Yep, I think this comes down to a limitation, but will let @fclem have the final word.

In Eevee, specular reflections of the light itself are "blocked" by the shadow maps (same as diffuse), these are not shadow rays.
This is a very simplistic example:

repro.blend

Cycles:
image.png

Eevee:
image.png

note this is all pure specular.

So yeah, one could says these are "wrong" in Eevee, but this is probably just the best you can get for area light sources in a realtime scenario (or is raytracing here a things as well nowadays)?
@fclem: dont see this mentioned in the documentation, maybe it should?

Yep, I think this comes down to a limitation, but will let @fclem have the final word. In Eevee, specular reflections of the light itself are "blocked" by the shadow maps (same as diffuse), these are not shadow rays. This is a very simplistic example: [repro.blend](https://archive.blender.org/developer/F10427851/repro.blend) Cycles: ![image.png](https://archive.blender.org/developer/F10427856/image.png) Eevee: ![image.png](https://archive.blender.org/developer/F10427866/image.png) note this is all pure specular. So yeah, one could says these are "wrong" in Eevee, but this is probably just the best you can get for area light sources in a realtime scenario (or is raytracing here a things as well nowadays)? @fclem: dont see this mentioned in the documentation, maybe it should?
Philipp Oeser changed title from EEVEE reflections bug or feature? to EEVEE lighsource reflections bug or feature? (shadowmap blocking) 2021-09-16 14:59:10 +02:00

Shadowing (or visibility) is not generally separable from shading but for realtime rendering purpose we consider this to be true as we only have shadowing information for one direction.

I guess this could be added as limitation of the shadow system in the documentation.

Raytracing the shadow map is not going to fix it because we will still only stick to the separability assumption to avoid twice the cost of shadows (which will be very high for raytracing).

Shadowing (or visibility) is not generally separable from shading but for realtime rendering purpose we consider this to be true as we only have shadowing information for one direction. I guess this could be added as limitation of the shadow system in the documentation. Raytracing the shadow map is not going to fix it because we will still only stick to the separability assumption to avoid twice the cost of shadows (which will be very high for raytracing).
Member

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

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

thx sharing the info @fclem

I guess this could be added as limitation of the shadow system in the documentation.

Will set to TODO then.

thx sharing the info @fclem > I guess this could be added as limitation of the shadow system in the documentation. Will set to TODO then.
Philipp Oeser changed title from EEVEE lighsource reflections bug or feature? (shadowmap blocking) to EEVEE lighsource reflections bug or feature? (shadows being used for visibility could be documented) 2021-09-27 12:15:49 +02:00
Aaron Carlisle removed the
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Eevee & Viewport
label 2023-02-08 04:57:42 +01:00
Aaron Carlisle added the
Module
Eevee & Viewport
label 2023-08-13 15:15:50 +02:00
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Reference: blender/blender-manual#89556
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