Fig. 3. A trigonometric point with signal during the field surveys. 
por 
# 
  
Fig. 4. Test target for investigations of the variation of the resolving power. The 
3 
variation ratio of the magnitude of the lines is chosen V 2. The seven groups of 
lines correspond to the values (lines/mm) 13, 16, 20, 25, 32, 40, and 50 respectively. 
The length of the lines is five times the width. The scale factor of the photographs 
about 1:813 for c — 150 mm.