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placed bv computational procedures and was thus able to improve
the precision by way of eliminating instrumental errors occurring
in instrumental bridging. By so doing, only the formation of
individual models was done at the instrument (analog or analytical)
whereas the bridging, formation and adjustment of the block was
being performed off-line at a computer. Numerous tests x^ere per
formed world-wide. One can refer to the works of F. Ackermann,
G.S. Schut, G. Inghilleri, E.H. Thompson, G. Togliatti, S.K. Ghosh,
C.W. King, V.A. Williams and H.H. Brazier, to name a few (for
references, see Ghosh 1975). Yet, further block triangulation
studies continued (Ackermann 1966, van den Hout 1966). One found,
however, that the more a block is subdivided into the elements,
the simpler the equation structures became. On the other hand,
the problem of obtaining the adjusted values became more cumber
some. Thus, the various methods of adjustment procedures would
not be basically different in the theoretical formulation of the
fundamental equations, but they would differ in the computational
procedures needed to handle a large amount of data and this in
order to solve systems with unknowns of other kinds, and to elab
orate procedures for evaluating the relative and absolute pre
cisions of the adjusted coordinates. This also required the skill
of the computer technologist rather than that of the photograra-
metrist. People were looking for "tricks” in the computer util
ization rather than in the photogtammetric procedures. Thus, of
necessity, people were yielding to the computer. In the program
ITC-Jerie Anblock, the adjustment of planimetry is completely
different from that for altimetry (van den Hout 1966). Obviously
such approaches were inspired by previous works of recognized
experts (Ackermann 1964, Jerie 1964).
By the end of 1960s one finds that the use of analytical photogram-
metry was no longer limited to research institutes (academic or
national mapping related organizations). It began to be used (due
to the operational ease, obtainable precision and rapidity of
production.) in the private sector together with the commercial
ization of programs developed at the institutes. For example, the
Stuttgart University program developed under the direction of
Ackermann reached world-wide diffusion, as well as subsequent
programs like RABATS developed by J.F. Kenefick associates and
SPACE-M (or PAT-M) developed by the Canada Department of Energy,
Mines and Resources.
B. Analytical Aerotriangulation
The major thrust of completely analytical aerotriangulation has
been in the U.S.A. Inspired and initiated by people like Schmid (1959),
the basic approach involves the observation of image coordinates only.
The elemental unit is not the model any more but the photogram and the
implied condition is that of collinearitv of the optical ray containing
the perspective center (camera station), an image point and the correspond
ing object point. During the development, however, there have been several
digressions.
