i imported a 2 km² landscape, that is part of a cityengine scene. the mesh has a low resolution since the terrain is pretty even.
for some reason i get some dark areas on the landscape when lit. i already tried to deactivate lumen and raytraced shadows, increased the lightmap size, changed the landscape material and checked for any kind of cloud shadows. none of those settings seem to have any impact.
on the screenshot you can see the difference between the lit and unlit terrain. there are no hills or trees that could cast a shadow in this area, just a photo texture. the terrain can also receive shadows with a high resolution if other objects are placed on the surface.
any ideas how i can fix that problem?