Managing Large 3D Urban Databases

The three dimensional digital data of objects of a city has shown to be a powerful tool for many applications. Namely the planning of wireless networks in cities, the support of decision making processes for urban development projects, the simulation of pollution distribution or the support of civil and military security operations. Today the initial commercial driver for the creation of such data for entire cities is the telecom industry, optimizing their communication networks depending on line-of-sight analysis. In addition to the presentation of the shape of urban objects we have observed the need for an enhanced realism of these data by exploiting the radiometric information of images. Creating such fully three dimensional city scapes has turned to be the key technology for a various number of novel applications, even if the acquisition of missing source data and the maintenance and administration of these huge amount of data needs to be better organized. Remote and local access to the data, fast interaction and electronic links to other urban information systems turns this into a concept of a hypermedia data base system, which is the unavoidable next step in improving the data for the management of our growing cities. The basic instrument of this technology is the digital graphics workstation, which is able to handle and visualize large sets of vector and raster data. In line with this development of graphic computers, we observe a strong development in the domain of computer graphics applications, namely methods and algorithms to organize, handle and visualize digital graphics data. Methods for the documentation of existing objects exploit these skills in addition with the well-known techniques of image data acquisition, photogrammetric processing, surveying and GIS technologies. In this contribution we discuss several aspects of the digital documentation of large objects like an entire city and focus on interactive data