BUNDLE ADJUSTMENT FOR 35 MM OBLIQUE AERIAL-PHOTOGRAPHY

The full provision of ground control points for oblique, small format photography used for mapping purposes is uneconomic because each photograph covers a small area of ground This paper describes the implementation of a bundle adjustment program for 35 mm oblique aerial photography. Image co-ordinates are measured on enlarged prints, with a digitizing tablet driven by Carte MDSD software, and are then processed with the NLHBUNT program. The measurement system was proved by using vertical standard format photographs of a test block saturated with high quality around control. Measurements taken with the MDSD system gave acceptable accuracy when compared with a set taken with a Zeiss P3 analytical workstation. A bundle adjustment was then carried out with the MDSD data; the results obtained compared satisfactorily with known ground values. A hand-held 35 mm Pentax LX camera was flown over the test site and three strips of 1:30 000 scale oblique photography were obtained. Following bundle adjustment, the empirical accuracy of derived co-ordinates was about 1.5 m in X, 3 m in Y and 2 m in Z. Factors affecting this accuracy are discussed and further developments of the system are proposed.