Static Mesh planes and Landscape do not properly implement "Shadow Two Sided"

Found bug in 4.9.2, confirmed to persist in 4.10.1

To Recreate:

Create blank project, delete SkySphere_bp, clear everything except for:

  1. a blank post process (just make sure to set indirect illumination intensity to 0 so there is no ambient lighting)
  2. A default, dynamic Directional light
  3. A static mesh plane, or a landscape, set to material that does not have a flat normal map. Make sure to check the “Shadow Two Sided” boolean is set to true on both.
  4. Make sure to re-build the lighting to clear any old lightmaps
  5. Set directional lighting to an upward angle, but not completely perpendicular to the plane and landscape. My picture uses a 50 degree upward angle.

Note that the normals of both the landscape, and the plane surface are being lit when they definitely should not be.

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Bump. Very easy to reproduce. Can’t see this being intended behavior.

Bump. The same results are produced even if the material is “two sided”

Hey HuntaKiller,

Thank you for taking the time to report this issue. I was able to reproduce this issue on my end and entered a bug report for this issue, UE-24656. One this issue has been fixed, it will be integrated in an upcoming full release or hotfix.

If you have further questions, please let me know.

Thanks,

Just wondering if this has been looked at at all by the team or if its just on the to-do list, I haven’t been able to find a workaround that solves the problem without removing the sunrise/set.

It is still on the to do list. I will add community interest to the bug to help give it a higher priority.

The issue has been set as “Won’t Fix” can we re-open it? I would really want to get it fixed, for this issue is bothering me so much and I don’t want to end up placing planes under the map to keep the light from leaking.

Hey Kristjanmn,

I just updated the ticket internally to reflect your concerns. If we are able to review the issue again and get a fix, it will be reflected on our public JIRA once the fix has been made.

Thank you,

Bug tracker was closed again

How dumb “no one has complained about this bug in a while so we won’t be fixing it”.
I’ll make sure to complain about this more. Epic this is a ridiculous bug, why are surfaces lit from the wrong side? Reopen and address this!

bump… they just did reworked the landscape rendering pipeline… seriously…
I get that this isn’t a part of the LOD / Tessellation but its also a shadowing issue…

This is still an issue, years later.

Bump. Still not fixed