Hey Everyone,
I’m having an issue when using Ambient Occlusion in the latest UE4 4.8 promoted branch. When I apply an unbound post process volume and activate ambient occlusion, I get a serious amount of artefacts on screen and jittering on the effect - these are persistent no matter the intensity or values that I apply to the settings. This is also an issue once the game is built and not just an “in editor” problem.
When using the same post process volume in the same scene in UE4 4.7, the AO renders correctly and with no issues.
Due to some of the console optimizations that are only implemented in 4.8, we can’t revert back to 4.7. I’ve attached a couple of comparison screenshots as well as a video Illustrating the issues we’re having with AO in 4.8. Is there anything you can think we might be able to do to solve this issue?
LINK TO VIDEO (download for higher quality) - Microsoft OneDrive - Access files anywhere. Create docs with free Office Online.
Please note that we are not using DFAO and it is not enabled in our project settings.
Thanks in advance!
Thanks for the quick reply Andrew - Here is a screenshot of the settings on both UE4 4.8 and 4.7.
Nothing is different but the results are drastically different - I should also note that no matter how much I edit and tone the AO down in 4.8, I still get the jittering and artefacts :(. One thing I do notice however is the lack of an “Occlusion Distance” option in 4.8. I don’t use it in my 4.7 scene anyway, but thought I’d mention it :).
Cheers,
Hello JHBurton,
Would you mind providing me with your Post Process settings you have for Ambient Occlusion in your project?
Just in case you have not given it a look already, here is some documentation on SSAO and some of the nuances on how to get it to work correctly and effectively.
Ambient Occlusion (SSAO)
Let me know if you discovered any new information on your issue after reading over the documentation, or if any new questions arise you need help answering.
Cheers,
Hey ,
Tested what you are reporting and was able to confirm what you are reporting. I have gone ahead and entered a bug report for this issue (UE-13256).
Thank you for taking the time to report this issue, and if you have any further questions or comments regarding the issue please let us know.
Regards,
Hey Andrew,
Thank you for reporting the bug. I appreciate your help with all this.
I know it might be impossible for you to say, but is there a potential ETA on this as it’s a severe bug issue that is hindering our game release?
Any help or information you can provide on this would be hugely appreciated!
Kind Regards,
Since it was just reported, I honestly cannot give you a time frame in which this fix will be implemented. We always post the new releases and hotfixes on our Forums, so you can look there for updates on the issue.
However, a workaround would be to try and combine materials with Ambient Occlusion and a smaller degree of your SSAO within the post processing. This will reduce the amount of flickering and hopefully still give you the strong AO you are attempting to use.
Cheers,
Thanks Andrew,
Hopefully this will get resolved soon :). Thanks a lot for your help!
Regards,
I optimized and quality improved SSAO recently. This is from our engine news ans something similar should be in the UE4.8 release notes
Improved/Optimized Screen Space Ambient Occlusion:
- Recently, we have fixed some issues with the existing ScreenSpaceAmbientOcclusion - mostly to support a larger radius and to get rid of an artifact (halo that was hard to prevent - even with tweaking). There is an intended look change and in some cases you might want to tweak the parameters or remove your old settings. If possible stick to the defaults.
The new implementation is a bit more noisy but that should be rarely noticeable.
I think because of your old settings you see it being much worse that I’ve seen it. Especially strong and small radius SSAO settings will look worse. There is an optimization that makes small radius bad - but it can be disabled with a single line change:
find this in PostProcessAmbientOcclusion.usf
// 0:normal method using depth computed in setup passes
// (might need a clear outside the viewport, test with stereo/splitscreen)
// 1:faster but slightly lower quality
#define USE_HZB 1
We’ve seen the artifact this optimization causes but with large radius settings it’s quite fine. Still - we intend to change the HZB slightly to gte the quality we had before.
I suggest you first go for the default SSAO settings, maybe tweak them and if needed you change the define (might have to change other things) and as last resort you could undo all changes to the SSAO (made by me).
Please keep me updated.
Hey ,
Sorry for the late reply - Things have been pretty crazy around here! haha.
Changing the radius to be much larger seems to help a lot. Right now we managed to get something that looks decent - We still get some flickering (that is noticeable on meshes that are white, I guess because of the contrast) but it might just be okay for now. Thank you so much for your help, it’s really appreciated!
Regards,
Hi there, i’ve recently (yesterday) posted a similar question i realize. I used latest 4.12 and have some similar issues. I will have to experiment some more to see how i can tone down these artefacts. But wanted to link these two answerhub questions: Issue with sliding AO shadows with movable lights - Rendering - Unreal Engine Forums
Any additional information about this and steps how to minimize/compensate for the artefacts will be much appreciated.
