59 
  
  
T T T 2 n 
I T 
10 20 30 40 50 
Diagram 13. Ordinary aerial triangulation. Standard errors of the three angles of the 
exterior orientation. Cantilever extension. s, — l. 
so = 0,01 mm the standard errors are graphically demonstrated in 
diagrams 13— 14. 
In a similar way the accuracy of the elements of the external orienta- 
tion can be determined for other geometrical conditions. We will later 
on demonstrate how convergent aerial photography can be treated. 
€ 
3.2. The error accumulation formulae for model coordinates 
In order to find the error accumulation formulae for the model coordi- 
nates from the corresponding formulae of the elements of the external 
orientation we have to use the differential relations between the elements 
of the external orientation and the model coordinates. 
The general formulae are wellknown and can be written as follows 
for a model r — 1,7 
(x — b)y xy (x? + h?) (x — b) _ 
De ir 5 Du, À ) Dx, m Dy, + 
p f(y — by h?} x — b)y 
l J : 1 
o. io Des 
m De, m (Do, _, Do,) + 
x (x — b) x — b Dx x Bx 990 
bh (Dbz,_, — Dbz,) — p PA 9^ (229)