IMPROVING THE DESIGN OF BLOCK TRIANGULATION IN ANALYTICAL PHOTOGRAMMETRY
Fabio Crosilla*, Gianfranco Forlani**, Tommaso Russo*
* Università degli Studi di Trieste
Trieste, Italy
** Politecnico di Milano
Milano, Italy
ABSTRACT
The purpose of this work is to show how it is possible to transfer to
analytical photogrammetry the FOD problem and the SOD problem. The used
method consists in choosing a target value for a function of the va-
riance-covariance matrix of the unknowns and in a repeated solution of
the SOD problem, cancelling in each times the observations with a non
significant or non significative weight. Some numerical examples of so-
lution of the SOD problem are executed for four blocks of a different
number of strips. Block adjustment is performed by bundles. For all the
examples two different target values of the trace of the covariance ma-
trix are fixed. Each pair of collinearity equations is considered with
the same group weight.
From the obtained results it is possible to state that, in almost all
the cases, the SOD can be used successfully to optimize the plan of the
observations, by about the same number of observations.
1. INTRODUCTION
The importance and the very wide diffusion which analytical photogram-
metry has been assuming nowaday as a Survey and control technique, are
due to the presence on to the market of high precision analytical plot-
ters and powerful and efficient computing facilities. Automatic com-
putation can be carried out by algorithms developed in the past for re-
latively small and slow computers which can be performed today on faster
computers with large central core available,
Furthermore, the similarity of deterministic and stochastic models en-
countered in both analytical photogrammetry and geodesy permits an
interchange of computing algorithms between the two fields. This is the
reason why the tentative is made to test the optimal design techniques
that have already been applied to geodetic networks in the last decade,
to the field of analytical photogrammetry.
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