An Approximate Camera Calibration Method

Abstract

An approximate camera calibration method without using any photogoniometer or angle measurement was tried for the preliminary calibration of the taken camera. A flat terrain with vast quantity of canals, rivers and ditches was selected and the heights of water surface was measured with a precise plotting instrument at many points scattering over the stereo-model.
After adjustments of model inclination and the effects of the Earth's curvature, the height discrepancies at each points from the datum plane was expressed as the function of bi-polar coordinnates, which has their poles at the principal points of the two photos.
Assuming a polinomial form for the distortion, the residual bight discrepancies were computed and compared with the measured values And the distortion polinominals was corrected by iteration.
Actual analysis was carried out graphically, with not so high accuracy which can not be expected from such a approximate method. Also, the determination of the principal points on the photo-plane was not tried because of the poor resultant accuracy which may be expected from such a approximate method.