Eevee's AO shades even outside of the distance #82462

New Issue

SecuoyaEx · 2020-11-06T15:12:52+01:00

SecuoyaEx commented

2020-11-06 15:12:52 +01:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71

Blender Version
Broken: version: 2.90.0, branch: master, commit date: 2020-08-31 11:26, hash: 0330d1af29

Short description of error
Eevee's AO creates certain amount of gradients and shading even outside the Distance area. I'm not refering to the typical screen space oclussion problems.

For example, if you turn Distance to 0, instead of getting the same result as having AO turned off, you get a gradient. Here's how it looks with a flat lit, diffuse scene:

Distance 0, Factor 0:

Distance 0, with a Factor of 10 to exagerate the effect:

Even if the gradient is subtle with Factor 1, it can be very visible in certain workflows. Example: There are no other screen space effects in this image, other than AO, which has small distance anyway but this gradient spans the entire image (I'm aware that 360 is not officially supported but still, the gradient itself is not a fault of the 360 stitching and can be a problem for regular images too

If this is a limitation of the method, may I suggest a clamping slider of some sort for very light values? Thank you❤

Exact steps for others to reproduce the error
Open the file and turn AO on and off
AOBUG.blend

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71 **Blender Version** Broken: version: 2.90.0, branch: master, commit date: 2020-08-31 11:26, hash: `0330d1af29` **Short description of error** Eevee's AO creates certain amount of gradients and shading even outside the Distance area. I'm not refering to the typical screen space oclussion problems. For example, if you turn Distance to 0, instead of getting the same result as having AO turned off, you get a gradient. Here's how it looks with a flat lit, diffuse scene: Distance 0, Factor 0: ![0factor.png](https://archive.blender.org/developer/F9218543/0factor.png) Distance 0, with a Factor of 10 to exagerate the effect: ![10factor.png](https://archive.blender.org/developer/F9218544/10factor.png) Even if the gradient is subtle with Factor 1, it can be very visible in certain workflows. Example: There are no other screen space effects in this image, other than AO, which has small distance anyway but this gradient spans the entire image (I'm aware that 360 is not officially supported but still, the gradient itself is not a fault of the 360 stitching and can be a problem for regular images too ![360.jpg](https://archive.blender.org/developer/F9218587/360.jpg) If this is a limitation of the method, may I suggest a clamping slider of some sort for very light values? Thank you❤ **Exact steps for others to reproduce the error** Open the file and turn AO on and off [AOBUG.blend](https://archive.blender.org/developer/F9218541/AOBUG.blend)

SecuoyaEx commented

2020-11-06 15:12:52 +01:00

Added subscriber: @SecuoyaEx

Philipp Oeser commented

2020-11-09 10:07:06 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-11-09 10:07:06 +01:00

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

Philipp Oeser commented

2020-11-09 10:07:06 +01:00

Can confirm.
No idea about the underlying method used here, so might be a Known Limitation, but cannot find it documented anywhere.

may I suggest a clamping slider of some sort for very light values

Not sure what you mean, treat zero as AO disabled?

Can confirm. No idea about the underlying method used here, so might be a Known Limitation, but cannot find it documented anywhere. > may I suggest a clamping slider of some sort for very light values Not sure what you mean, treat zero as AO disabled?

SecuoyaEx commented

2020-11-09 14:18:17 +01:00

Not sure what you mean, treat zero as AO disabled?

No, I mean a slider to clamp the light values to white. Given that the most interesting, more "proper" AO stuff happens in darker values.

Here's a mockup with a factor of 5, with a factor of 1 it would be even more subtle.
Unclamped:

Clamped:

I would do this with the compositor but there are two other problems.

One is the AO pass doesn't take into account Bent Normals, Bent Normals gives different AO with different HDRI. I think this is another bug worth reporting
The other is that the diffuse pass always includes the AO, so there's no way to exclude it properly, given that the AO is supposed to be multiplied only against the enviroment light and the result summed to the rest (as it should), not multiplied over the entire image. Without an enviroment light pass or light groups, is cumbersome to do with the current View layer system, losing all performance benefits

>> Not sure what you mean, treat zero as AO disabled? No, I mean a slider to clamp the light values to white. Given that the most interesting, more "proper" AO stuff happens in darker values. Here's a mockup with a factor of 5, with a factor of 1 it would be even more subtle. Unclamped: ![ex1.jpg](https://archive.blender.org/developer/F9245231/ex1.jpg) Clamped: ![ex2.jpg](https://archive.blender.org/developer/F9245232/ex2.jpg) I would do this with the compositor but there are two other problems. One is the AO pass doesn't take into account Bent Normals, Bent Normals gives different AO with different HDRI. I think this is another bug worth reporting The other is that the diffuse pass always includes the AO, so there's no way to exclude it properly, given that the AO is supposed to be multiplied only against the enviroment light and the result summed to the rest (as it should), not multiplied over the entire image. Without an enviroment light pass or light groups, is cumbersome to do with the current View layer system, losing all performance benefits

Philipp Oeser removed the

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Eevee's AO shades even outside of the distance #82462