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In such systems digital mini-computers tend to be the central. They assist in data procure 
ment, accomplish various types of handling, and control analogue components. More 
over, mini-computers provide for high flexibility, versatility, accuracy, increased 
speed, and improved operational conditions. 
The equipment components can be arranged modularly and may operate on-line or 
off-line. The problem of linking digital and analogue components has been simplified 
considerably by the currently available standard interfaces. The present availability 
of fast-accessible backing mass-storages at acceptable prices tends to overcome the 
problem of the limited computer’s central memory. 
In the concept of automated large scale restitution (which is also applicable to small 
scales) the D. T. M. data serve as the common input. This requires the creation of 
D. T. M. storage - retrieval systems (data banks). These data can then be used either 
directly for the various conversions (e. g. contour lines, profiles, volumes, etc.), 
or indirectly to control analogue components (e.g. orthophoto printing, drafting maps, 
etc,). 
In order to meet specifications for various applications, D. T. M. data should be com 
prehensive and sufficiently accurate. A potential method of generating such data is 
by progressive sampling. This method implies the ability to adapt the local density 
of a point grid to the variability of terrain relief. 
Among the various automatic processes based on known D. T. M. data printing of 
orthophotographs is the only typical photogrammetric one. Optical printers require 
less pre-processing for the control of printing, but their efficiency, accuracy, 
flexibility and versatility seem inferior to electronic versions. 
A non-automatic photogrammetric application of D. T. M. data is digital mono-plotting, 
in this approach the planimetric line-and point data of a single photograph are merged, 
by means of a computer, with the corresponding D. T. M. data, and transformed into 
the data to be plotted. Such systems may be highly flexible and versatile. The metric 
operations, photo-interpretation, and cartographic editing can be separated better 
«than in conventional stereo-plotting, which permits the employment of appropriate 
personnel in pach phase. The main applications of digital mono-plotting might be: 
i 
- map revision and frequent re-mapping; 
ithematiq mapping; 
jf mapping from non-conven Tonal image records.