Ahhhh! I have this on a landscape! Nobody answered me - good luck :-/
I cannot figure out what’s causing the lightmaps to fragment when baking. Here’s the problem in action:
Preface: Lightmap densities are sufficiently high, meshes have no UV distortion and proper lightmap UVs, lights are all set to static, world settings are at default.
Problem: Whenever lightmass bakes lighting, the final lightmaps look as if they were run through an 8-bit blender. I’ve tried disabling compression, changing the lightmap resolutions (which are sufficiently high), moved the assets and lights to a completely new map…and still no change. I’m completely stumped as to what could be causing these issues. Any help is appreciated.
If anyone from Epic reads this: the lightmass baking calculations are causing rendering artifacts on mesh backfaces even when two side flags are toggled on the mesh and material domains. The only solution to prevent backface artifacts is to create “extruded” geometry.
In case you’re reading this later…
Finally figured this out. In short, the artifacts will occur during the light baking process and will appear on the backfaces of objects (keyword being backfaces) even if flags are toggled to make the mesh behave as if if were being lit on both sides. The mesh shown in the original image above has a 2-sided material applied on it with the “Use Two Sided Lighting” flag toggled, thus the assumption was that the mesh would be lit correctly with Lightmass. BUT, because the faces were in fact backfaces (aka, the tent interior was flipped outwards), the outside of the tent would light correctly, but the interior would display the 8-bit like artifacts.
This is where the problem resided…backfaces will artifact, frontfaces will not.
To correct this, I inverted the mesh normals so they would be facing inwards (the side I wanted to be lit). The other rendering flags (aka, “Two Side” were still set for proper calculation, so no changes there). The final mesh (as seen in Maya) looks like the following:
Finally, since the faces were flipped, it was entirely possible that light would bleed from the backside of the faces when baking lighting from directional lighting; causing unnecessary/inaccurate lighting artifacts. To combat this in UE4, I simply created a low res shell to cover the entire tent structure and act as a light blocker.
Could very possibly!
Would this also apply to landscape?..