Geometry and Information Contents of Large Size Digital Frame Cameras

Large size digital aerial frame cameras like Intergraph DMC and Vexcel UltraCam are becoming standard for photogrammetric application. It is difficult to compare the information contents of such cameras with this of analogue photographic cameras. Also the rules for project planning have to be checked if the old relation between photo scale and map scale is still valid. The photo scale has no longer any meaning for flight planning because it is depending upon the pixel size in the camera; the important figure is the ground sampling distance (GSD). The image quality of digital cameras usually is quite better like the image quality of scanned photos, disturbed by photo grain. The comparison of digital images taken with different GSD and scanned analogue photos are leading to the result, that digital images have the same information contents like analogue photos scanned with 20μm pixel size having a GSD smaller by the factor of approximately 1.5. That means 15cm GSD from a digital camera is corresponding to 10cm GSD from analogue cameras scanned with 20μm pixel size. So the information contents of a DMCand also an UltraCamD-image exceeds the information contents of an analogue aerial photo. Block adjustments with digital camera images are resulting in sigma0 values of 0.15 up to 0.3 pixels. This high accuracy potential cannot be reached by analogue photos. But it has been shown, that self calibration by additional parameters is still required also for original digital images. Because of the small field of view, the systematic image errors are causing not negligible model deformation. If the systematic image errors can be used in the processing chain, the full accuracy potential of the digital cameras can be used. A program for geometric improvement of the images by the systematic image errors and a program for the improvement of height models by the model deformation have been developed in the Leibniz University Hannover.