The Terrain of Star Trek Elite Force 2 levels is decompiled with the visible surface on the top - always.
( https://github.com/search?q=repo%3Awfowler1%2FLibBSP+terrainDef&type=code )
stef2_terrain_face_source.zip
If you have a cave, the floor would be visible but the ceiling would not.
If you then noclip ontop of the cave you see the surface that is suppose to be on the inside (ceiling) of that terrain part.
