Sarjakoski (1981) has outlined a Concept of a completely 
digital stereoplotter. Conclusions here are: 
e 
* The technology for designing a completely digital 
stereoplotter is already available. Still, it is not 
yet possible to handle very large digital images 
  
(expressed in picture elements) such as aerial 
photographs. 
* The biggest advantage of a completely digital 
stereoplotter could be achieved in applications 
where the results of photogrammetric measurements 
must be quickly available and where the resolution 
  
  
requirements are not extremely high. 
  
* The need for developing a completely digital 
stereoplotter will become more actual when the 
resolution of digital cameras is as good as that 
  
of conventional metric cameras. 
The U. S. Defense Mapping Agency (DMA) has been involved in 
the development of a digital plotter, in order to improve the 
throughput and response time of map production. Case (1982) 
describes the features of the DMA system then under 
development: 
* Stereo viewing of two CRT displays by means of 
pinocular optics, with a third CRT for an overview 
display. 
* Real-time image movement with the ability to roam 
over the whole model area. 
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