Abstract
Abstract. Z/I Imaging introduced with the DMC II 140, 230 and 250 digital aerial cameras with a very large format CCD for the panchromatic channel. The CCDs have with 140 / 230 / 250 mega pixel a size not available in photogrammetry before. CCDs in general have a very high relative accuracy, but the overall geometry has to be checked as well as the influence of not flat CCDs. A CCD with a size of 96mm × 82mm must have a flatness or knowledge of flatness in the range of 1μm if the camera accuracy in the range of 1.3μm shall not be influenced. The DMC II cameras have been evaluated with three different flying heights leading to 5cm, 9cm and 15cm or 20cm GSD, crossing flight lines and 60% side lap. The optimal test conditions guaranteed the precise determination of the object coordinates as well as the systematic image errors. All three camera types show only very small systematic image errors, ranging in the root mean square between 0.12μm up to 0.3μm with extreme values not exceeding 1.6μm. The remaining systematic image errors, determined by analysis of the image residuals and not covered by the additional parameters, are negligible. A standard deviation of the object point heights below the GSD, determined at independent check points, even in blocks with just 20% side lap and 60% end lap is standard. Corresponding to the excellent image geometry the object point coordinates are only slightly influenced by the self calibration. For all DMCII types the handling of image models for data acquisition must not be supported by an improvement of the image coordinates by the determined systematic image errors. Such an improvement up to now is not standard for photogrammetric software packages. The advantage of a single monolithic CCD is obvious. An edge analysis of pan-sharpened DMC II 250 images resulted in factors for the effective resolution below 1.0. The result below 1.0 is only possible by contrast enhancement, but this requires with low image noise, demonstrating the very good radiometric image quality.
Highlights
Digital frame cameras nearly totally replaced analog photogrammetric cameras
In general the bundle block adjustment should be done with the standard set of 12 additional parameters, with this the root mean square differences at the check points is for X and Y between 0.25 and 0.6 ground sampling distance (GSD) depending upon the image overlap and the GCP accuracy, for the always more critical Z-component it is between 0.5 and 0.9 GSD
All analyzed blocks taken by the different DMCII versions have systematic image errors clearly smaller as for all other handled cameras
Summary
Even if digital line scan cameras as the Leica ADS40/80 and the Jena Optronik-JAS150 do have a satisfying performance (Jacobsen et al 2010) they are not so much accepted as replacement of analog cameras. The capacity of the large format cameras recently has been extended with the DMCII versions and the UltraCam Eagle. Very large digital frame cameras have an extended requirement for the sensor geometry. In the case of a reduction of the pixel size smaller systematic image errors are extending their size in relation to the pixel size. By these reason geometric tests for the new cameras are required
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