Most analytical plotters resemble the US-2. 
The analytical plotter consists of several main components: 
o A precision stereo viewer on which two overlapping aerial pho 
tographs are placed to form a stereomodel. This pair of pho 
tographs, if properly oriented, allows for three dimension 
viewing and for accurate measurements to be made. Measurements 
are made by recording X and Y coordinates of the same image on 
photographs 1 and 2. These measurements are made through the 
use of precise linear encoders and the photogrammetric trans 
formation computations are made quickly by a high speed micro 
processor, in real time, converting those measurements to 
ground positions in any specified coordinate system. 
o A high speed micro processor is designed to compute in real 
time all of the operations required to compute photogrammetric 
computations, coordinates the photographic stage movement with 
the operator's signals that are given by use of handwheels or 
other guidance system. In efficient analytical plotters, this 
micro processor is used to relieve the load on the host com 
puter. 
o Host computer - this is a mini computer of high quality and 
capability. It works in concert with the micro processor. It 
also pro-vides all the application programs needed to make an 
analytical plotter efficient. This host is the medium for data 
transfer from the analytical plotter to any data base and com 
puter assisted mapping system. 
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