I know that terrain is a different thing than the models or blocks, however, I was trying to place some prefab huts and stuff on my level and noticed that I couldn't use the CSG subtract tool/option on the terrain model. I created the terrain using photoshop and it's just a random heightmap basically. It doesn't have places where I can conveniently fit building prefab models into the landscape. So I was going to cut holes for them and it didn't work. Maybe I'm doing something wrong? I don't have the terrain object locked or excluded or anything, I checked. I just wanted to confirm that I would be unable to use the CSG subtract feature on terrain models. Thank you in advance for any help .