The landscape is not solid when you create the scenery and place assets on the terrain in the Editor. I actually like that because it allows to decrease some assets in its height and hide the unneeded parts under the surface when the locations favors it and you want to do so. I don't actually know if there is an option to make the surface solid, but it is not necessary for me because when I drag assets on the terrain, they usually snap automatically to the ground. Isn't that the case, when you do so? Only when you play the game the terrain is as solid that your player or train does not "fall through" the terrain.
I forgot something to say. Some house assets even have like a fundament part attached at the bottom which I think is meant to be / or at least should be put under the surface. Probably it has been made for the creation and should be hidden in this way. Look at that. This wouldn't be possible if the surface were solid:
If I'm in select mode, and I want to place a cube from the place actors menu, its not being placed on the surface
I've never understood the functionality of that function. Lukas explained it in way I couldn't understand. Well, that actually solves some time to me too when assets are not snapping.
