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: rectify a digital image of a building facade using at least a Hough linear transformation; subdivide the digital image into image regions; determine similar horizontal layers by detecting vertical symmetry in a vertical direction; determine similar vertical columns by detecting horizontal symmetry in a horizontal direction; generate an irreducible facade structure with horizontal layers reduced to non-similar horizontal layers by stacking up the similar horizontal layers, and with columns reduced to non-similar columns by stacking up the similar columns; determine in the irreducible facade structure horizontal splitting lines which divide the facade into floors, and vertical splitting lines which divide the facade into tiles; subdivide the tiles into a hierarchy of rectangular image regions by aligning horizontal splits within horizontal rows of tiles, and aligning vertical splits within vertical columns of tiles, based on information about horizontal and vertical repetition of similar tiles included in the irreducible facade structure, wherein subdividing the tiles uses a recursive process of selecting a best splitting line for each of a plurality of image regions, the recursive process comprising initializing all tiles, selecting a best split candidate for each region, synchronizing splits of tiles within a same group, globally synchronizing all split candidates, subdividing the regions into new smaller regions, and recursively repeating the recursive process until no non-subdivided regions remain; 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, without requiring user input, the 3D geometric model or the definition of the 3D geometric model based on the 3D architectural objects determined.