It is offered to use digital models of a relief and digital models of a surface for recognition city territories and detecting of change of their condition. For this purpose construction DEM and DSM is carried out automatically on stereo models of aerial photographs. The dense digital model of a surface with the step calculated according to the theorem of Kotelnikova for revealing of objects of the set size is created. Calculating differences of heights between a relief and a surface, receive values of heights of objects. On the basis of this data it is possible to define, for example, этажность buildings. Besides receiving differencing models on stereo models received for two dates define changes in a condition of city territory.