The application of this approach to terrestrial networks is described in /11/. 
Since two dimensional photogrammetric free blocks are built up by models in a 
similar way as terrestrial networks by triangles or closed polygons, one may 
expect that the same artificial matrix applies also to the variance covariance 
matrix of the coordinates resulting from the photogrammetric free block 
adjustment. Several examples of eigenvalue computations in photogrammetric 
blocks are given in /4/, the paper by J. van den Berg, also presented at this 
symposium. Together with the results of other investigations, for instance by 
Molenaar in /8/, and /7/, it is justified to state that the precision of a free photo- 
grammetric block behaves similar to the precision of a free terrestrial network. 
This means a strong agreement between G and H, especially if the boundaries of 
the block are ignored. The boundaries are less involved in the free adjustment, 
which causes a lower precision. ; 
Nevertheless, in practice a sufficient approximation of G by H is reached. 5o, in 
the free block, one value Ox, will be sufficient to indicate the precision and 
enables one to construct H for the free block. 
In view of the comparison to the eigenvalue problem of the constrained block later 
on, the general eigenvalue problem of the free block is now elaborated as: 
  
  
| Ge uH, I "ing 
or 
gl! gl? | od oul 
- = 0 e 
A acit "ae 22 (4.2) 
f f c=1 
2 3 1 : 
With x. orthogonalized with respect to Xe as in (2.5): 
11 11} ı2 
I 0|| G; 0 Dac G, 
2d - 
213 31 222 
I 
; 1/10 G. 0 
(4.3) 
li 11; l.i? 
I of IH 0 ; H H 
2111 | i 22 FU 
HH 0 - 0 I 
c=1 
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