Bundle block adjustment with ultracamD images

Abstract

Large blocks of UltraCamD images have been taken over the area of Istanbul. The high accuracy of the digital images together with crossing flight lines allows a reduction of the number of ground control points against the rules of thumb for analogue photos. By simple theory a calibrated digital camera should not show systematic image errors - we do have no problems with film flattening and film deformation. But the bundle adjustments showed the requirement of a self-calibration. Special additional parameters, able to correct the position of the 9 sub-images of the UltraCamD, have been introduced into the used program system BLUH. Block adjustments with different control point configurations and different sets of additional parameters have been investigated. In general there is a clear improvement of the accuracy of independent check points by a block adjustment with self-calibration. Especially with a smaller number of control points the vertical accuracy is quite better with it. Against the standard set of 12 additional parameters the set of 32 special parameters for the UltraCamD could not improve the results even if the shape of the systematic image errors is similar for all sets. The dominating effect of the systematic image errors is the radial symmetric component, which must not be caused by the camera geometry. The high accuracy of the digital camera seems to allow a larger control point distance in relation to analogue photos.