3D CITY MODELS FOR CAAD-SUPPORTED ANALYSIS AND DESIGN OF URBAN AREAS

A joint research project was conducted at ETH Zurich to develop a user -friendly software environment for the representation, visual manipula tion, analysis and design of urban areas. Three groups were involved i n the project: (1) the 'Architecture and Planning' group defined the r equirements and expectations for the system; (2) the 'Photogrammetry' group acquired and processed raster and 3D vector data to form a 3D mo del of the urban area; and (3) the 'CAAD' (Computer-Aided Architectura l Design) group embedded the data into AutoCAD and implemented databas e functionality. Results of the photogrammetry group are presented, in cluding the implementation of a 'topology builder' which automatically fits roof planes to manually or semi-automatically measured roof poin ts in order to create AutoCAD-compatible 3D building models. Digital o rthoimages and derived products such as perspective views, and the geo metric correction of house roofs in digital orthoimages also were gene rated for test sites in Switzerland.