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THE INFLUENCE OF GROUND CONTROL ON PHOTOGRAMMETRIC POINT DETERMINATION 
Jan van den Berg 
Delft University of Technology 
Department of Geodesy 
Thijsseweg 1l 
2629 JA Delft, Netherlands 
ABSTRACT 
The block adjustment with independent models can be separated into 
two steps. The first step refers to the free block adjustment, that is 
only the x- and y-coordinates are considered as observations. In the 
second phase the connection of the free block with terrestrial ground 
control takes place. This is done by a so-called pseudo least squares 
adjustment. In this kind of adjustment the observations (the x- and 
y-coordinates of the control points themselves) get no correction 
after adjustment, but when evaluating the precision, their variance- 
covariance matrix is taken into account by applying a special case of 
the law of propagation. 
In this paper the results are shown of a number of experiments, which 
had the aim to get some information about the precision and reliability 
aspects of this connection. 
1. INTRODUCTION 
One of the results of the ISPRS congress 1984 in Rio de Janeiro was 
that in the following years more research should be carried out on the 
connection of aerotriangulation-blocks with terrestrial ground-control. 
This task was assigned to working group III.l. Then Molenaar proposed 
that the dutch members of this group should pay their attention to 
precision and reliability aspects of this connection. 
The so-called "Delft approach" of these aspects is now presented by 
De Heus [3] and the author of this paper. 
Whereas De Heus gives some theoretical background information about 
the theory involved, this paper shows some results of experiments 
which were carried out with artificial independent model blocks (2D) * 
However, before going into the experiments and their results, first 
an addition to the theory will be given in chapter II, namely the 
calculation of the boundary values in the second phase of the 
adjustment, so-called pseudo least squares adjustment. In this phase 
the connection between the free independent model block and the ground 
control takes place. 
* Although investigations on 3D-blocks are foreseen the presented 
results refer to the 2D-system. 
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