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.