There is, in my opinion, no good answer to such questions, except that given possibilities tend
to realize themselves. A kind of ’’horror vacui” seems to be operating by which real potential is
substantiated and turned into reality with great thrust, as soon as given a chance, independent
of whether the results are urgently needed or not. The preconditions and inherent features of
the process make it a self-accelerating feed-back process. It seems to stem from some basic traits
of western civilization which is progress-prone to a certainly unhealthy degree.
Such background considerations, however, remain totally irrelevant. Certainly, as far as pho-
togrammetry and remote sensing is concerned, there is no option. We are part of the technical
development and are carried away with it, pushing it happily ourselves. We take advantage of
it and harvest the benefits, to the better performance and the extension of our discipline. That
the development shakes us up somewhat and causes certain instabilities, must be considered
normal. Evolution always goes in jumps and produces discontinuities, independent of whether
those who are in it feel totally comfortable.
2 The Technical Development in Photogrammetry and Re-
mote Sensing
2.1 Let us review quickly some main development steps which photogrammetry and remote
sensing have taken during the past 25 years. Here, only the essential features are of interest,
independent of the detailed paths through which the actual development evolved.
It has been said often enough that since about 1970 photogrammetry went essentially from ana
log to analytical, although some analog elements still prevail, especially the continued use of
photography. At present the step from analytical to digital is being taken, still with analog,
and analytical elements continuing. The driving force in general has certainly been, and still is,
the digital computer and its vastly increasing performance and potential.
2.2 We may distinguish a first phase of development in the 1970s which can be characterized
as coordinate or computational photogrammetry and which is generally called analytical pho-
tograrnmetry. Within it several milestones can be identified:
The first milestone covers certainly photogrammetric point determination, aerial triangula
tion, block adjustment. It started simple enough as improvement of previous methods of aerial
triangulation and was in the beginning still struggling with previous concepts and with poor
computer performance. However, and tins is the point to which I want to draw the attention as
a general feature, it soon grew out into completely new performance which changed the situation
thoroughly. The development led to a more fundamental approach, and soon the general multi
station solution of the photogrammetric orientation and point determination problem emerged,
pushed even further by the self-calibration method. The result was increased accuracy, at least
by a factor 20, and an enormous step in economy, by the implied simplification, by the reduction
of ground control points, and by the inclusion of auxiliary data and external constraints. Soon
aerial triangulation was generally applied in practice, and completely new applications appeared,
as for instance cadastral photogrammetry, photogeodesy, as well as special applications in close
range photogrammetry or in mapping the moon.
Other milestones in the development of analytical photogrammetry of similar weight can be
cited. The analytical plotters and the analytical orthoprojectors have made analog instru-
