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A. Analytical aerial triangulation
The theoretical foundation and the development of the main computer programmes
(Stantec Zebra ITC) for the method of analytical aerial triangulation according to the
method of Van den Hout, have been achieved in the period before 1960. Van den Hout
(Rijkswaterstaat and ITC) has reported about it during the Analytical Conference Week
in Milan, 1960 [40]. In completing this system of analytical aerial triangulation during
1960-1964 a number of additional computer programmes have been developed at the
ITC, concerning for instance the use of réseau photography and correction for earth cur
vature, see [5], [6]. A major extension has been developed by I. Levy (ITC) who has
worked out a very general computer programme for analytical aerial triangulation which
can incorporate measurements both from analogue projection instruments and stereo
comparators [53]. Special care has been taken to correct for known instrumental and image
errors. A textbook representation of analytical photogrammetry has been given by F.
Ackermann (ITC) [4].
The further contributions to the theory and practice of aerial triangulation are mainly
concerned with adjustment procedures or they have been developed in connection with them.
B. Adjustment procedures. Analytical block adjustment procedures
In 1960/61 F. Ackermann (ITC) developed a method of least squares strip adjustment
following the well-known approach of Vermeir and Baetslé. The method has been worked
out for height adjustment and planimetrie adjustment separately [1]. It has been pro
grammed for the Zebra computer by H. F. Soehngen, and is since in practical use. Exten
sion to the simultaneous adjustment of x,y, and z-coordinates is developed and has been
studied by G. C. Agarwal (Thesis ITC), but is not yet programmed.
The well-known ITC-Jerie Analogue computers for block adjustment about which
H. G. Jerie has reported at the Analytical Conference Week in Milan 1960 [44] have been
subject to further operational research and extensions: I. Levy has worked out a computer
programme (Zebra) for a semi-analytical procedure which takes care of all numerical
computations involved in the ITC-Jerie analogue method of planimetrie block adjust
ment [52]. The planimetrie analogue computer has been modified to incorporate scale
information from APR data. An extra analogue computer has been developed to adjust
azimuth data in blocks with cross strips, see [47].
The problem of analytical block formation and block adjustment was tackled from two sides:
In the group TH-KLM a set-up for planimetrie block adjustment was developed by
Sonnenberg working with independent models. Later on M. Tienstra developed a proce
dure for height adjustment of a block following an idea of C. M. A. van den Hout, also
working with independent models. Both approaches have been programmed by IBM.
In the group ITC-Rijkswaterstaat it was C. M. A. van den Hout who made an approach
for planimetrie block adjustment with independent models. He made special use of the
linearity of the system of unknowns and the occurrence of many zeros in the coefficient
matrices of the normal equations. A short description of the method was given by Van den
Hout during the Munich Photogrammetric Weeks, 1963*. This approach was taken up
at the mathematical department of the ITC and worked out into a computer programme
(Zebra) of great flexibility.
* H. Kasper, Bericht über ein neues ITC-Verfahren für die rechnerische Blockausgleichung nach der
Methode der kleinsten Quadrate, Schw. Zeitschr. f. Verm. 1964, 1.