64 
Consequently from (255) and (256) 
b 
ma = 7 So 
and 
h? 
Qua = (257) 
Dé 
After substituting (257) into (251) the latter expression is referred to 
the same standard error of observations as (250). Consequently 
; ; n [5 | 
Q, = Q TQ, = 7 172 (27: + 1) + (2n + 1) (n + D (258) 
TnTn TnTn TnTn 6 | d? 
For b — d and after some rearrangement we have 
n 
Q = — (4 n? + 3 n + 2) (259) 
nn 6 
The weight number (259) of the x-coordinates is evidently determined 
with respect to the first pair of photographs —1,0 as fixed and free 
from errors. This means a certain approximation. As demonstrated 
by HALLERT 1957 the influence of the errors of the first model of a 
triangulation upon the x-coordinates of the open strip can be expressed 
with a weight number 
T. 
Nr 
RT 
N 
N 
mi " + - ! 260 
rer p? p^ q? b (200) 
where x is the x-coordinate referred to the principal point of the photo- 
graph —1. 
For x — bn we find from (260) 
ha 
Q' 2 - n -—2n4-2 (261) 
va b? d? 
Assuming b — d — 0,6 h we find with a minor approximation 
, 
gr 10 n° 2n + 2 (262) 
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