line in the opposite direction in order that the so-called Fertsch effect 
should come into view. 
At 185 points indicated on the map, the measuring of elevation was 
carried out. The elevation of the 185 arbitrarily chosen points had earlier 
been determined by geodetic measuring with a tachymeter. 
Analysis of accuracy 
The planimetric plotting was examined in the following way: 
1. The coordinates were transformed (Helmert) to the geodetic system 
using the control points of the models as given points. Table 3 shows 
the coordinate standard error in the transformation points as well as in 
the eight signalled control points. 
Table 3. 
Unit — metre 
Flying altitude .... 600 metres (1: 4000) 450 metres (1: 3 000) 
Emulsion : Panchromatic Colour Panchromatic Colour 
Tex ceu ee ^m Bos 2 Seules od 
Standard errors of unit weight in the transformation points 
N ES 0.035 0.041 0.031 0.038 
Number of redundant observations .. 6 6 14 16 
Geodetic part ...-9 4. erre « 0.025 0.026 0.025 0.028 
Photogrammetrié part ............ . 0.024 0.032 0.018 0.024 
  
Eight signalled controlpoints 
Root mean square ................ 0.055 0.052 0.064 — 
For the whole material so — 0.036 metres with 65 redundant observations. 
According to tests on the Öland field (Moren, 1967) the geodetic share 
in the standard errors has been calculated by quadratic subtraction. This 
gave 0.027 metres for the whole material. 
2. Regarding other planimetric details (about 120 points), no compari- 
son was made with the geodetic measuring. The object of the analysis 
was to show the differences between various stereo plottings and within 
the same stereo plotting. The planimetric details were divided into 
groups and the precision of the situation is shown in Table 4. 
DD 
N