Semi-Automatic and automatic extraction of objects from aerial images

Different methods for the extraction of objects from aerial images are presented. Unlike other methods which process the complete image systematically, object guided methods were developed which are applied only to those parts of the image where objects or parts of objects have already been detected, i.e., where a continuation of an object is probable. Basic principles as well as details of the extraction methods are explained. The methods differ with respect to the local precision of the results, the applicability to different object types and the required image quality. Local operators are described which evaluate grey level diagrams in order to detect object continuations. The methods were implemented on a computer DEC PDP 11/70. Results are presented.