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).
Highlights
White to paie yellow, slightly consolidated sand is widely exposed on eastern Disko below the Tertiary vo1canic rocks
The Eagle metric cameras of the type 'EagIe' between 1948 and cameras used in the 1940s and 1950s for oblique pho
This is a relatively highvalue comseribes an experiment where such photographs have pared to the results obtained with modem cameras and been used for mapping of steep mountain sides for the film types, but it is notof great significance' in the production of geological maps, cross-seetions and per-. present experiment, and we were able to orientate three spective views
Summary
Large areas in Greenland are covered by oblique aer- nos 8840 and 8841 from 1949 taken with an Eaglecamial photographs, taken with 23 x 23 cm photogram- era no. 15 is used as an example (fig. 1). This is a relatively highvalue comseribes an experiment where such photographs have pared to the results obtained with modem cameras and been used for mapping of steep mountain sides for the film types, but it is notof great significance' in the production of geological maps, cross-seetions and per-. Vo1canic units are traced from dose to likely sources of the large residuals Geologists their eruption sites, where they originate as subaerial should be aware during the planning stage that not all lava flows, to where they enter water-filled basins and old photographs are of sufficient geometrical quality. The standard errors on the scale in the orientated model were better than 1%0 in spite of the Photogrammetric orientation fairly large co-ordinate deviations This was found to be satisfactory because the aim of the present experiment. . 80% overlap was lIscd and is rceommendcd for future work ahhough Ihe accuracy af Illcasurcmcnl is abDUl half that for 6()O/o overIlIp
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