When building lightmaps for landscapes - if it is at 0,0,0 rotation, it all works fine, yet when rotated in any way it causes huge black splotches everywhere.
I posted the issue a while back, and have recently found the issue again with any landscape with any rotation values.
Although the more the rotation, the worse the artifacts. 90 degrees, for example, will produce a few in various areas whilst 180 degrees will ruin the entire landscape.
##Repro Steps
Action 1: Create landscape by importing a heightmap.
Action 2: Rotate landscape - via the creation tab or after creation.
Action 3: build lighting.
##Additional Information
Lightmass settings don’t impact the issue.
Static lightmap resolution and LOD of the landscape don’t impact the issue.
This issue effects both landscapes created in editor and imported height-maps from World Machine.
Unfortunately at the moment we do not have a public bug tracker. This is being assessed to see what we could do in the future about implementing a public feature, however I don’t have a timeframe of when that could/would be made available.
If it helps your investigation, I’ve found that the black splotches are caused by the landscape shadows - rather than any other object casting shadows on the landscape.
Turning off “cast static shadow” gets rid of the splotches - but of course this no longer looks as good as it should, since the landscape no longer casts shadows, but it does show that the cause isn’t shadows cast by foliage or any other object in the scene.