1. A system for generating a 3D (three dimensional) geometric model and/or a definition of the 3D geometric model from a digital image of a building facade, the system comprising: a computer system comprising one or more processors, said computer system programmed to implement at least: a structure detector configured to subdivide the digital image into image regions; an architectural element library comprising 3D architectural objects; an element detector configured to determine in the architectural element library 3D architectural objects corresponding to the image regions; and a generator configured to generate the 3D geometric model or the definition of the 3D geometric model based on the 3D architectural objects determined.