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Identifying Kurt Franz Camera
Page A4
Appendix A - Identifying the Kurt Franz Camera
More precise photogrammetric procedures were unmerited. It would have entailed control points in the scene, camera calibration, and a knowledge of camera tilt, roll, and pitch angles. This data was obviously not available.
Illustration of Data Fit
The image in Figure A5 demonstrates the fit of the angular measurements plotted on transparent overlay materials fitted to the aerial photograph. The overlay was rotated and translated until each line intercepted the corresponding conjugate image feature as closely as possible. As can be seen in the illustration, the fit was quite close. The next step was to ensure that the range measurements agreed with the distance from the camera station through the visual fit procedures. This step provided a cross check. If the wrong camera had been assumed, the range measurements and angular orientation of the camera cone angle could not have been reconciled. As it turns out, the distance of the camera station established by the visual fitting, to the position indicated by the intersection of the three range loci (shown in the next figure) is only about 7.5 meters [24.6 feet]. This figure is a very satisfactory error considering the tremendous number of unknowns and the many sources of errors in the methodology. The same procedures were used in two other cases where ground photos of the living camp were available. In addition, all the candidate camera systems were evaluated. Only the Voightlander Bessa characteristics yielded a good fit of the angular data to the aerial photography.
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