When using Google 3D Tiles, virtual shadow maps, and “Ignore KHR_materials_unlit” enabled, I get constant shadow popping, sometimes when the camera gets closer. Is there a fix for this?
Video:
This doesn’t happen with OpenStreetMaps buildings, only Google 3D Tiles.
Hi @Salakin, welcome to the community!
Thanks for including a video of this behavior. This issue might be related to the general behavior of 3D Tiles. Since tiles are selected based on the camera view, the shadows can change depending on which tiles are hidden or shown. This Github issue describes the issue in further detail: Tiles that are not visible do not cast shadows · Issue #285 · CesiumGS/cesium-unreal · GitHub
However, it’s possible that using virtual shadow maps exacerbates this behavior. Our team might not be familiar with how to use those in Unreal – could you describe how you’ve set them up? Ultimately it would help the most if we could reproduce this in our own environments and take a closer look.
Assuming this is just the usual “culled geometry doesn’t cast shadows” problem, you can find more information about it in this tutorial section. There are also some tips there for minimizing the problem.