Originally posted on the forums here (image of issue in post), and has already been discussed with an Engine dev in the forums.
Contact shadows currently have major rendering artefacts on small meshes, especially when far away from the origin. Posting here for consistency.
Hi Jamsh,
Contact shadows have always been a bit grainy since their inclusion in 4.13 (was considered experimental). I noticed you said your mesh is very small, depending on just how small you can definitely expect some precision issues. For example if your mesh could fit inside a 0.0001 cubic cm.
I can put in a feature request for you, the request can ask for additional settings to allow smoothing out the grainy nature of contact shadows. However, this isn’t a bug per say just a new feature that needs improving upon.
,
Ed
Hi Ed,
On the forums, another Epic staff member told me there are actually some issue, it doesn’t used transformed position for the lighting?
My mesh isn’t small enough that it will fit into a space that size, it’s about 40 units accross. On an object that size the contact shadows are completely unuseable.
Hi Jamsh,
There was a bug logged but it got marked as by design.
There is something going on here and contact shadows are still being looked into. So it is possible that the status of this bug report will change. I’ll update you once a decision is made in regards to this issue.
Just updating you, we are still looking into this currently. Things are moving along a little slower than expected, but I still plan to let you know whats going on once more information is available.
Hi Jamsh,
This was determined to be a bug and has been issued a fix for the next patch. Thank you for your post along with some other vocal users. It helped us convince us that this was a real issue that needed looking into.
Here is a link to the public JIRA: Unreal Engine Issues and Bug Tracker (UE-38768)
regards,
Ed
The JIRA lists this as fixed but in UE4.14.3 contact shadows are still producing artifacts. Was this fixed in UE4.15 cause even though the JIRA says it was fixed, it’s not.
Can confirm, in my tests contact shadows are not only extremely spotty (in 4.15), but also flicker like hell. If I wanted to create a Mosquito swarm it wouldn’t be too bad as it looks almost like this but other than that it hardly can be used for anything.
I can confirm this is still an issue in 4.26 and was never fixed. Neither was the flickering, the only way I could get it to stop flickering like a disco ball begging to send someone into an epileptic seizure was by changing the Anti-Aliasing to TemporalAA because FXAA and MSAA both made me want to have a seizure. The worst part about this was that I discovered the issue in the new Rural Australia package released.