Determination of radial and tangential distortion of reseau cameras with the Helsinki University of Technology horizontal goniometer

Abstract

The radial distortion and its asymmetry, the tangential distortion, the mutual positions of the fiducial centre, principal point of autocollimation and point of best symmetry, and the calibrated focal length have been determined from two Canadian réseau cameras, Zeiss RMK AR 15/23 No. 21197 and Wild RC-8 15U Ag. R 10 No. 107 with a horizontal goniometer in the Helsinki University of Technology in 1974. The radial distortion was determined from the two diagonals and two diameters parallel to the frame sides in all in 124 points for both cameras. The tangential distortion was calculated from bending observations of 12 diameters of the frame plane. In the Zeiss réseau camera there was a great asymmetry in radial distortion (PPA-PBS was 45 μm) and its maximum azimuth in the frame plane was the same as the 0-axis of tangential distortion, which had the maximum values of 14 μm. In the Wild camera, the asymmetry of the radial distortion was very small and the values measured for the tangential distortion were below 1 μm. Some results have also been compared with those measured by Carl Zeiss Oberkochen and Wild Heerburg. In all 10 wide-angle aerial cameras (6 from Carl Zeiss Oberkochen and 4 from Wild Heerbrugg) were measured with the Helsinki University of Technology horizontal goniometer in 1974–1975.