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most efficient way to do this, is subject to further testing. Currently, the implementation of image
processing and photogrammetric algorithms from the 'old' DSS is under way. An example may
just give a first clue for the obtainable speed-up: A bilinear interpolation resampling algorithm
that processed a 1200x1000 pixel image on the VAX11/750 within 15 minutes just needed 70
seconds on a network with two worker transputers.
CONCLUSIONS
Today's digital photogrammetric systems in principle already have the capacities of analytical
plotters and, moreover, are adding a lot more. At present they still have some limitations in disk
storage, screen resolution, and general processing speed but these should be overcome in
the near future, considering the rapid hardware evolution of recent years. Particularly interesting
are new processors designed for parallel data processing and thus promising a much more de
cisive speed-up than new single processor architectures. In this paper an Advanced Digital Ste-
reophotogrammetric System based on the INMOS transputer family is discussed. It is a comple
tely modular approach and expandable as user needs demand and budget allows. Since it is
running under the distributed operating system Helios which provides the user interface and
the standard tools known from the Unix system it enables users to create applications that are
independent of a certain transputer network constellation.
This is an important assumption for portable software of lasting value and justifies the compa
rably high development costs arising when starting a new system from scratch. The results of
first tests confirmed optimistic predictions and encourage the authors' persuasion that after an
initial phase, which is naturally longer than with turn-key systems, the ADSS is going to be a sy
stem that not only fully substitutes an analytical plotter but also opens new application fields in
industrial and scientific branches such as medicine, robotics, material testing and the like. Skep
tics should be aware of the fact that digital photogrammetry today is in a position very similar to
that of analytical photogrammetry some ten to fifteen years ago (BONJOUR & NEWBY 1990)
when new analytical plotters appeared on the market.
