[ISP Commission II, Invited Paper ] 1 
Trends in the Development of Computer Supported Analogue 
Instruments 
B. Makarovic 
I Introduction 
The object of this paper is to give a critical review of the present state 
of the art and the future trends in the area of computer supported analogue 
instrumentation for photogrammetric restitution. The scope has been to present 
an overall outline of the area and some fundamental considerations on interac- 
tivity between the analogue and digital components. Thus, it does not pretend 
to report exhaustively on the present status of the equipment development. 
Digital components can be integrated in photogrammetric restitution 
systems in different ways. Regarding the way and degree of involvement of a 
digital computer, a distinction can be made between fully digital type 
systems, hybrid systems and computer supported conventional instruments. 
Each of these three categories can be differentiated further. 
The digital type systems can also be classified into the stereo- and mono- 
systems and the on-line and off-line systems. This paper has been devoted to 
the on-line computer supported conventional stereo-instruments. These have 
been classified into the systems with a uni- and bi-directional flow of infor- 
mation and into single and multiple systems. 
The development concerning integration of digital computers in photo- 
grammetric equipment was initiated in the USA, 1953, by Paul Rosenberg 
Ass. (1). In 1957 U.V. Helava (then NRC, Canada) formulated the concept of 
the Analytical Plotter, which was the beginning of the fully digital approach. 
The approach implies a maximum involvement of digital components and thus 
uses a minimum of mechanical parts. This development has continued in the 
USA. 
In Europe the evolution has been gradual from analogue to increasingly 
digital. The development was initiated with a minimum involvement of digital 
components, supplementing a conventional instrument. About 1960 Zeiss 
Jena developed a co-ordinate recording device the Coordimeter A, with a 
simple digital computer (with relays) incorporated (2). Since the computer 
capabilities were very limited, it was abandoned in the later versions. 
In 1968 Bendix Co. developed in the USA an experimental computer 
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