1. A computer-implemented method for removing hidden faces in a 3D building model, comprising: identifying a 3D building model having hidden surfaces, wherein the hidden surfaces are hidden inside the 3D building model; adding, with a computing device, closing surfaces to the hidden surfaces to form closed hidden surfaces; combining the closed hidden surfaces into a single polygon such that the single polygon is representative of the hidden surfaces and the closing surfaces, wherein the combining facilitates effective removal of the hidden surfaces from the 3D building model; and removing the single polygon from the 3D building model such that the hidden surfaces and the closing surfaces are removed from the building model.