Tip: Import 3D Model

For whatever reason, some 3D models have to be imported in Mathematica.
The 3D model is stored as OBJ file. When it is imported, it loses the texture information.

(* set the color *)
roof = Import["greenroof.obj"]
roof = roof /. {l_Line :> {Thick,Black, l}, p_Polygon :> {FaceForm[Darker[Green]], p}}

Here the whole model: