In 2014 the surveying and mapping administration of North Rhine-Westphalia (Geobasis NRW, located at the Cologne Government Regional Office) provided, for the first time, a statewide national 3D-building model in the level of detail 2 (LoD2: integrated standardized roof forms). It consists of 10 million buildings. The whole derivation process was fully automatized using available reference data of the cadastre and airborne laser scan measurements.
After this first derivation of the 3D-building model, additional tasks are necessary to handle existing errors. Buildings are interactively corrected by the use of oriented aerial pictures. These changes are stored in the data base of the 3D-building model.