The pattern of the blocks and the shape of the networks are illustrated 
in the fig. 4.1 and 4.2, for the two examples respectively. Both cases 
refer to real schemes of measurements, but the observation values are 
simulated. : 
The photogrammetric data concern image and model coordinates, so the 
aerial triangulation adjustment is performed by bundles and by indepen 
dent models. 
The control points are established: 
- in the first case, by a leveling network for the altimetry and by a 
triangulation and transverses network for the planimetry; 
- in the second case, by some leveling networks and by points belonging 
to the surface of three lakes for the altimetry only. 
  
All the data concerning the adjustment, its computation and the statistics 
of the results obtained are shown in Table 4.1. The analysis of this 
table allows for the following remarks, 
= The joint adjustment combines the advantage obtained by the network 
adjustment and by the block adjustment separately. The flexibility 
of the input format is obviously higher than that one of the block 
adjustment and the price to pay in terms of additional complexity 
is very small. The high performance of the reordering algorithm (see 
also the next remark) and of the linear algebra routines are essential 
to obtain the solution in about the same computing times as in the 
case of separate adjustments. 
7 The optimization of the non-zero elements in the normal matrix for 
the joint adjustment gives often a profile with right margin, due to 
big connections coming, for example, from the measurements of 
distances or directions. In this cases the gain obtained by the new | 
version of the reordering algorithm is always a significative ratio 
of the core memcry request necessary to store the profile. Therefore, 
in order to evaluate the performance of the reordering algorithm, the 
same must be mcdified as shown in the appendix. 
= The joint adjustment can be used instead of the block adjustment, in 
order to establish the control points. Indeed the geodetic network 
that links the control points, can be formed by various disconnected 
subnetworks. This situation occurs often for technical leveling: 
some fictitions origines permit to use these networks without addition 
al surveying measurement operation. 
= The network densification for cadastral, or planning, or civil 
engineering purposes and the control problems at local and regional 
scale seem to be the main fields for the application of the joint 
adjustment, Indeed in these problems fundamental is a high level of 
precision, such as the correct applications of the least squares joint | 
adjustment furnishes if the measurements are of high precision too 
and the redundancy is high. For this reason the photogrammetric block 
of the joint adjustment Test of the Commission A OEEPE seems to be | 
too weak. 
  
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i 
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T" 
  
Finally, since an interesting experiment of joint adjustment for 
cadastral networks densification has nowbegun in Italy with a coopera 
tion between University researchers and other Administrations, a new | 
real example will be hopefully available soon. | 
———————ÓMMÓMÓáá 
  
  
ACKNOWLEDGMENTS: The authors thank very much Mr. Luciano Pallottino, 
who has skillfully drawn the figures. 
  
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