a. Performs automatic compilation of orthophotographs 
in latent-image form. 
b. Performs automatic compilation of form-line contour 
charts in latent-image form simultaneously with the orthophoto 
compilation. 
c. Records on magnetic tape terrain-surface coordinates 
during the orthophoto compilation. 
27. The AS11B/C model, which was delivered in July 1966, 
combines the above capabilities into one instrument which will 
be described in more detail later in this paper. 
28. The one example of a digital approach tc automatic map 
compilation has been the studies, investigations ana development 
carried out by the International Business Machines Corporation, 
Kingston, New York, under contract with GIMRADA during the period 
1961 to 1964. Some further in-house studies are being carried out 
by GIMRADA on this Digital Automatic Map Compilation System. The 
contractual experimentation employed an IBM 7094 computer and 
an experimental digital scanner-printer, combined with a Wild 
STK-1 stereocomparator. The scanner-printer was an electro-optical- 
mechanical device which used the STK-1 stereocomparator as both 
a measuring machine and a scanning bed. A line scan CRT was the 
light source for scanning and printing. Recording was by means 
of optical elements which directed the light beam through the 
diapositive in a point by point, line by line sequence to the 
photomultiplier which measured the transmissivity of each minute 
area. After orientation of the diapositives on the stereocomparator, 
the input diapositives were scanned and digitized in the overlapping 
area at a resolution of 16 spots per millimeter. 
29. While the system was designed to convert images to digital 
data at levels up to 64 gray shades, it was operated at 8 levels 
because of the signal to noise limitations of the experimental equip- 
ment. The digital information was stored on magnetic tape so that 
each photograph was represented by a matrix of numbers. Using 
this digital data, measurements from the stereocomparator, and 
information supplied by the resection-orientation program, the 
photographs were rectified digitally. The process of determining 
the location of conjugate images in the two photographs was performed 
by utilizing statistical methods of matching density differences 
of spots and groups of spots. The measurement of the parallax 
of these conjugate images was then converted directly to elevation 
differences of the terrain. The individual point elevations comprised 
the necessary input data for producing the contour manuscript and 
also for shifting the photographic images in order to form the 
orthophotograph. All of this digital processing was performed in 
an off-line IBM 7094 computer. In printing the output manuscripts, 
the magnetic tape containing the corrected data was fed to the 
Printing element, which actually was the scanner performing a 
reverse function, i.e., the digital data modulated the CRT light 
source, exposing light sensitive film. The orthophotograph was 
therefore exposed by modulating the light to the required density 
level and the contours were printed by exposing the light at all 
spots which fell at the predetermined contour elevations. 
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