Serious issue with ambient occlusion after upgrade to 4.15

Hi, we upgraded our project to 4.15 some days ago, and we are fighting with a terrible issue without finding any solution.

The issue is on ambient occlusion, it appears and disappears on different camera angles, and it makes it only in PACKAGE. In editor everything works like a charme!

This is a shot from a camera angle which makes AO disappearing:


Then, turning to another angle the AO appears again and stays there if I don’t move the camera.

Our lighting setup is:
Movable directional light with raytraced distance field for far objects and cascade for near objects
Stationary skylight with:

  • Dynamic shadows off
  • Static Shadows on
  • Distance field AO disabled because of dynamic shadows off

Now, my suspect is that the bug is on the postprocess value “Static fraction”

Since if i set this to 0, AO disappears also in editor from my scene. If i keep it to 1, everything works in editor, but in package I have this AO glitch.

Anyone has a solution or an idea? This is a big issue for us, and I don’t really know how to reproduce it…

Thank you very much.


The error seems like the SSAO pass being FREEZED, look this screenshot:

That’s really weird… no one?

There is a known issue with SSAO getting frozen but it’s certainly lacking in solid reproduction cases, this is the first time I’ve seen it in the 4.15 release. Can you please report the bug here (More info) with your screenshots and mention it’s known? If you can reproduce this in a new project or could share more details on exactly what post process and lighting setups you’re using, that would be incredibly helpful! :slight_smile:

I will, thank you very much for the reply!!

Chris, unfortunately I can’t reproduce the bug.
It seems really random. I turned off and on this values and settings and the bug just disappeared:

occlusion culling
stop moving directional light
delete lightmaps

this fixed the bug, the weird thing is that once it’s fixed, if I set everything as it was before… it works! The bug just disappeared. But I really fear that he could appear again next week or next month for some random change.

Chris, I found the issue.
Disabling Custom Depth-Stencil Pass will fix the problem, but we are using it a lot so it’s a big issue for us! I’ll make a post into bug reports section, hope you can solve it as soon as possible…

I made a post into bug reports:

Just ran into this problem. Deleting the post process volume fixed the issue so something buggy there

If you delete postprocess you won’t have SSAO in scene, the problem is merging ssao and custom depth in my case. Disabling custom depth in editor project settings fixes it.

I disabled AO volume and if i use the default ssao the problem is still there. So for me the only way to fix that is disabling custom depth.