29 
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iistri TA3 
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Trips are 
in each 
weights 
for each 
The following adjustments were performed: 
1. A second-degree adjustment using two ground control points in each of 
the four corners of the block: numbers 3, 5, 40, 41, 271, 275, 297 and 299. 
2. A second-degree adjustment using in addition two points in the middle 
of the western and eastern sides: numbers 153, 159, 118 and 192. 
3. A second-degree adjustment using in addition two points in the middle 
of the northern and the southern sides: numbers 19, 25, 286 and 287. 
4. A third-degree adjustment using ground control points in the four corners 
of the block. Since the third-degree conformal transformation requires a minimum 
of four well separated ground control points, there is here no need for the iterative 
adjustment. 
In order to economize on time, not all four adjustments were performed with 
all three sets of strip triangulations. 
For the Zeiss Jena strips and for the Nistri strips, about 20 tie points were used 
in each overlap. For the Wild strips, about 24 tie points were used. 
Details of the iteration procedure and its convergence are given in Table I. 
TABLE I — DETAILS OF THE ITERATIVE ADJUSTMENTS 
Second-degree adjustments 
Zeiss 
Jena 1818 
Nistri TA3 
Wild A7 
on corner control 
0 
0.28 m 
6 
0.35 m 
0 
0.43 m 
20 
55% 
20 
55% 
28 
25% 
5 
10 
5 
on west and east control 
0 
0.32 m 
8 
0.32 m 
20 
45% 
20 
65% 
5 
10 
on perimeter control 
0 
0.20 m 
1 
0.09 m 
4 
0.14 m 
20 
60% 
17 
75% 
14 
60% 
5 
10 
10 
Key: 
(1) (4) 
(2) (5) 
(3) 
(1) Number of iterations performed with pairs of strips. 
(2) Total number of iterations performed. 
(3) Weight applied to the used ground control points. 
(4) Largest change in the transformed coordinates of any of the 18 known ground control points 
during the last four iterations. 
(5) Factor by which this largest change is smaller than the one during the preceding four iterations. 
Table I shows that for each of the second-degree adjustments of the Zeiss Jena 
strips 20 iterations were performed on all strips. Ground control points were given 
a five times greater weight than tie points in order to better enforce their position. 
The largest change that the position of any of the transformed ground control points 
undergoes is here reduced by about 50% each four iterations. With a largest change 
of 0.32 m during the 17th to 20th iteration, this means that after 20 iterations con 
vergence was reached to within a fraction of a meter.