272 
The areas in which the most active research and development work related to 
the instrumentation for processing and analysis of photogrammetric data is 
expected to concentrate in the foreseeable future are: 
- Analytical instruments 
- Automation of processes ; 
- Photogrammetric systems for establishment and maintenance of cadastral, 
cartographic and other land information data bases. ; 
- Photogrammetric digital systems for measuring, processing and analysis of 
digital imagery. 
- Instrumentation for true real-time digital photogrammetry and machine- 
vision. 
\ 
\ 
ANALYTICAL INSTRUMENTS 
Since the concept underlying the basic innovation leading to the design of 
analytical plotters is the incorporation of digital computing devices into 
the operator-image-operator feedback loop, these instruments may be defined 
as finite state digital machines for real-time addressing of photographs as 
two-dimensional arrays. Consequently an instrument with two photo-stages has 
four degrees of freedom, defined by four addresses represented by four photo- 
stage coordinates. Hence, the measuring of photo-coordinates is a function 
equivalent to addressing. This function is needed whenever an observation or 
a measurement is required, that is, in all cases involving the on-line, real- 
time operation of the system. Therefore the potentials and the limitations 
of analytical instruments are determined primarily by the structural 
characteristics of the image addressing components and interfaces. 
The implementation of a particular process on an analytical instrument 
requires the organization of proper sequences of logically complete 
elementary functions. These sequences consist of a combination of 
numerical operations performed by the computer and dynamic processes related 
to addressing performed by the positioning devices. Therefore the elementary 
functions are of two distinct types, that is, the functions concerning the 
transformation of some input data into some output data or return data, and 
the functions concerning the actions of system's physical devices (e.g. 
electro-mechanical devices). The latter are involved in all real-time 
operations while the former are "pure" computations that are in general time- 
independent and may be for all practical purposes regarded as off-line 
computations. Consequently very few instructions (i.e. macro-routines) need 
be added to the repertory of the programming language in order to perform any 
real-time process in any application of the analytical instrument. If the 
interfaces and the addressing devices are properly designed, only six 
additional instructions will allow for any possible action of the physical 
devices in comparator or plotter mode of the instrument (Jaksic, 1980). The 
proper interpretation and further analysis of the logical foundations of 
these design characteristics is. essential for the optimal design and 
evolution of future analytical instruments. 
A number of improvements in the design of analytical instruments are under 
way. Considering the cumbersome construction of positioning and measuring 
components based on electro-mechanical devices and moving assemblies, and the 
accompanying delays in their responses requiring complex controls, it is 
obvious that a departure from their present design principles is eminently 
necessary. A step in that direction is the superposition comparator design 
principle (Pekelsky, 1982). Also, the optical, image transfer components of 
analytical instruments offer little flexibility for the manipulation of 
transferred images. The use of electronic image transfer devices allow not