69 
Fig. 22. 
Map over points on the slopes of Rigi Kulm proposed as a test field for calibrating aerial 
cameras. With an exposure station 200 m above the top of Rigi Kulm the weight numbers 
of the camera constant and the principal points will be given in chapter 8.4.1. 
The conclusion is that the points on the antennas have to be determined at the 
same moment as the aerial exposure. This is theoretically possible but with the 
high requirements on the accuracy this is very difficult to realize in practice, 
because of the needs of expensive instrumentation and experienced personnel. 
Another possibility is to establish test areas in very mountainous terrain. 
Assume some 20 points, Fig. 22, well surveyed on the slopes of Rigi Kulm in 
Switzerland and a test photo exposed 200 m above the top of the hill. If it is a