<p>A three dimensional model of an urban area is produced by processing a stereo aerial view of the urban area to obtain a three dimensional map, identifying city units by correlation with a geographical database and obtaining ground level image data relating to city units from photographic or laser scan image data. Data from the various sources is correlated to provide a high resolution geographically accurate three dimensional model of the urban area. The viewpoints from which ground level data is obtained are shown on the model and are linked to the underlying image data such that the model further provides an integrated database. As a result an accurate, rapidly processed and easily updateable three dimensional model is provided.</p>
