Geological photogrammetry using oblique aerial photographs

Abstract

Large areas in Greenland are covered by oblique aerial photographs, taken with 23 x 23 cm2 photogrammetric cameras of the type 'EagIe' between 1948 and 1953. Though almost all of Greenland is now covered by modem vertical photographs, the oblique photographs still represent a valuable alternative source of geological information because of the perspective at right angles to the mountain side. So far, geologists have only been able to use the oblique photographs for visual interpretation. New photogrammetric instruments like the Kem DSR U/GPl Analyticai Plotter at the Institute of Surveying and Photogrammetry,the Teehnieal University of Denmark, make it possibie for geologists to map precisely from oblique photographs. This report deseribes an experiment where such photographs have been used for mapping of steep mountain sides for the production of geological maps, cross-seetions and perspective views. Earlier results are reported by Dueholm & Garde (1986) and Heinesen (1987).