Appendix A - Identifying the Kurt Franz Camera (Continued)
Shadow Height Measurements
The height of several features imaged on the ground shots was determined as follows. First, the sun elevation () and azimuth
() was established at the time the aerial
photography was exposed. The azimuth was measured directly on the aerial frame after it was accurately aligned with true north. Shadows cast by buildings and trees were
then measured, and an average taken. It was found that on the frames of the GX120 mission, = 90 degrees. That angle, in conjunction with the geographic coordinates
of the camp and the time of year, was then used to compute the local sun time (t) and elevation angle. The results were:
t =0634 AM, and = 24 50’.
The last step was to measure on the aerial photos the length of the shadows cast and then to compute the heights of the features casting them. This is given by elementary
trigonometry by:
Height = SL * Tangent()
.
Where: SL = shadow length, measured on the aerial photos.
Other Height/Ranging Measurements
The distance of objects from the ground camera whose height could be estimated with some confidence were also computed as a further check. Estimates relied
on internal clues contained in the images. Figure A3, shows a well and two of the Jewish workers. It has been enlarged from a Kurt Franz picture. A fairly
good assumption is that the height of the figure on the left is about 1.7 or 1.8 meters. Given this assumption, the scaled height of the structure used to support the windlass
shaft is 1 meter. The well shown here is also visible in the previous photograph
(
Figure A1
) as element number 6. To determine the distance from the camera station, one must knows
the height of the feature in object space; the respective measurement in the image space; and the focal length of the camera.
The distance to the object (D(o) is then given to a first approximation by the following equation (see Figure A4:)
) and azimuth
(
) was established at the time the aerial
photography was exposed. The azimuth was measured directly on the aerial frame after it was accurately aligned with true north. Shadows cast by buildings and trees were
then measured, and an average taken. It was found that on the frames of the GX120 mission, 
50’.
Where: 
SL = shadow length, measured on the aerial photos.
