- 5 - 
• A density wedge (to show range of shaded relief) 
• Digital, terrain-elevation data printed in a typed format 
Although these operations are essentially automated, human skill is required for 
stereoscopic identification of photographic detail, and for precise stereo measure 
ment of control points. In addition, the final editing of maps on photoscribing mat 
erials to conform to cartographic practice requires the skill of experts. 
The results of Systems I*and II*(as of June 1964) can be summarized as follows: 
Contour Factor 
Time to Produce 
Model on IBM 7094 
A.S.P. 
Stds. 
I.S.P. 
Stds. 
Contour 
Map Data 
Orthophoto Data 
and Contour Map 
System I 
> 250 
> 400 
* 
137 
System II 
> 180 
> 250 
45 min. 
59 min. 
The present accuracy of these output maps and orthophotos is limited by several 
equipment and programming factors. The errors in survey and calibration data 
will in time limit the accuracy of the System’s output. This fact suggests that cal 
ibration data for lenses, camera platens, and diapositive surfaces will be needed 
from testing laboratories on a point-by-point basis in the foreseeable future. This 
major problem is the basis for a Commission II Proposal contained in Appendix A. 
Processing Data for Cartographic Operations 
A special IBM drum scanner/printer was built at Kingston for experimental work 
on digital cartographic operations. This unit (Fig. 8) scans and digitizes a chart, 
photograph, or drawn overlay at a maximum spot density of 1,000,000 spots per 
square inch over an area up to 9 x 20 inches. The drum scanner/printer digitizes 
each spot at up to 16 shades of gray and records them on an IBM 727 tape unit at 
a 15 KC rate. Up to 540 million bits (each spot is usually 3 bits, to permit 8 shades 
of gray) can be extracted from the maximum area of 180 square inches. 
The data can be processed to perform some cartographic operations and to print the 
results on film. Examples of these operations are: 
• Changing chart, map scale, or projection 
• Removing distortions 
* System I produces the contour map and orthophoto data concurrently (if either is 
produced separately the time is the same). System II produces the contour map first, 
and then the orthophoto. Complete system diagrams are shown in ’’Automatic Map 
Compilation Using Digital Techniques”, referred to previously.