NERIS 
  
38 
pairs of photographs with respect to the accuracy of the intersection. 
Evidently favourable locations are 
b b 
A eem eem Scie E. os 
= 5 and y == + yz (123) 
which also can be proved from the expressions (8) and (9). 
b 
From the expressions (8) and (9) we find for 7 = 0 and y= + ] = 
9 
Que = Qu = 2 (124) 
From a comparison with the weight numbers (119) and (120) it is 
evident that the weight numbers (124) can be neglected in strips contai- 
ning only a few pairs of photographs. Therefore we will neglect the 
errors of the intersection of the control points when the error distribu- 
tion within the strip after the coordinate transformation is being in- 
vestigated. 
With a minor approximation the discrepancies in the control point in 
the pair of photographs n,n + 1 are regarded to be represented by the 
expressions (111) and (112). These discrepancies are compensated at the 
coordinate transformation by two translations, one rotation and one 
scale change of the entire strip. The differential expression of the coordi- 
nate transformation is again represented by the formulae (17) and (18). 
We denote the two control points by | and n. The coordinates of 
point 1 are approximately. 
X3 — 0 Y, = 0 
and of n 
X,.— bn Y_=0 
n n 
Hence we have the error equations 
0 — da, 
0 zz dU. 
db 
DX, = dx, + bn j 
) 
DY, = dy, + bn da 
n