Shadow seams in modular building generated by blueprint

supremedalek925

I created a blueprint that generates buildings using modular wall meshes.
I can't figure out why the shadows have very noticeable seams as can be seen here.  The mobility is set to static, same as the building made by modular pieces I just dragged into the scene (the one on the right), so I'm not sure where the difference is coming from.  Any ideas? Thanks

supremedalek925

I'm able to fix it somewhat using cascaded shadows, but there's these seams near the edges, and at a certain distance where the shadows fade out, there's no baked lighting in its place which doesn't look too good.

PatrickSF

It has to do with the way the building is being treated. In our heads it's a building, nice and complete, but as far as the light mass is concerned it's a bunch of pieces. The result you see is due to that and various other factors dealing with lightmass settings and the lightmap resolution of the ground.