3D reconstruction of urban environments is a widely studied subject since several years, as it can lead to many useful applications: virtual navigation, augmented reality, architectural planification, etc. One of the most difficult problem nowadays in this context is the acquisition and treatment of very large scale data if precise reconstruction is aimed. In this paper we present a system for computing georeferenced positions and orientations of images of buildings from non calibrated videos. Providing such information is a mandatory step to well conditioned large scale and precise 3D reconstruction of urban areas. Our method is based on the registration of multimodal datasets, namely GPS measures, video sequences and rough 3D models of buildings.