The following diagram exemplifies the separate effect of ¢, w, 
and x. The example assumes the right-hand picture to be truly 
vertical and the left-hand picture to be tilted and swung (1¢ in 
each of the orientation elements ¢, w, and x). 
  
  
  
Error in Ah +7 ] 
4e// 4^ 
c / = 4000 m 
Cd *67, es Dur v Ah = 30m, W- 1° 
+5 
24 d dh + 20m; w-/* 
+3 
+2 
+7 obs oce from center P picture 
according “© figure 
= Sem /ocem 
" > _ TT en avis ren bitrcent rer 
-} — S T ZONEN. fig: 
= ~ 
- x 
-£-| x x 
x e 
> \ 
£94 MN R MA Mom; 41“ 
N 44 « 0m; = / 
-4 À 
dh-30m, € 
a S. J 
r= 30m, #=/ 
will -] 
«7-1 
Figure 95. 
The error in height differences of 20 and 30 m for ÿ, © and % = 1°. 
In measurements by means of mirror stereoscope and stereo- 
meter it will be possible to keep x (swing of the picture around 
its centre) fairly low (c:a 0.5c). The following example shows 
the magnitude and the distribution of errors for x = 0c, ¢ and 
w = 3¢. The principle points of the left and right pictures are 
denoted 0, and 0; respectively. 
The examples show that relatively great errors (here as high 
as 13 76) can appear, and also that the o (or o) difference is not 
decisive for the magnitude of the errors, as is often said (the 
o difference is here 0c). o and «o can, of course, co-operate in 
different ways in respect of magnitude and direction. In the 
example, «) has been given a direction to produce an effect of 
error in conjunction with ¢. 
The errors vary very little with flying altitude, at least for 
altitudes between 2 000 and 6 000 m. With the same values of 
q and o as in the above example and for different flying heights 
id