26 
  
  
+3 + T3 + 
i^ *i MEE T 
+5 +6 +5 + 
  
  
  
  
  
  
Fig. 6. Location and notation of scale transfer points into models ;— 1, 4 and 7, à+1 
respectively. 
1.22. The error accumulation in the triangulation procedure 
In all observed data there are errors of various types present. When 
the observed data are used in functions as intersections and coordinate 
transformations the errors will propagate and accumulate. When the 
strip is transformed into the coordinate system of the ground the errors 
in the control points will become compensated by the elements of trans- 
formation but will become distributed to all other points. 
It is of fundamental importance for the triangulation procedure to 
study the laws for the error propagation, aceumulation and compensa- 
tion in order to be able to express the accuracy which can be expected 
from the triangulation under different conditions. 
First we will define some notations, see fig. 6. 
The intersected coordinates x, y of the points 3—6 which are 
demonstrated in fig. 6 are denoted as follows. 
In the image pair à — 12 
v. ; 
1454, . 
for point 4 
Yi—1,i4 
x. A 
11,6 . s 
for point 6 
Yi—1,i6 
v 
for point : 
for point 5 
- 
For simplicity we further assume all individual bases to be equal (b) 
and the points 3—6 to be located at the distance b from the bases.