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PHOTOGRAMMETRIC ENGINEERING 
processed and stored for use in direct conver 
sion of a digital photo to an orthophoto. The 
contour tape with rectification and relief dis 
placement data is converted to digitized 
orthophoto data. This data is moved once 
directly to its ortho-corrected position with a 
minimum number of data shifts. The output 
tape produced then contains the digitized 
orthophoto data ready for printout on film or 
diapositive, using the digital printing system. 
This program is complete and will work with 
rectified or (when available) with unrectified 
photos, using tabulated shift data. 
System Configuration 
EQUIPMENT 
The Digital Automatic Map Compilation 
(DAMC) system is built around an IBM 7094 
(Figure 3) Data Processing Unit (other proc 
essors of comparable power could be used) 
and the experimental DAMC photo-digitizer 
(Figure l).The photo-digitizer consists of two 
major sections: 
1. The Magnetic Tape Units and Mag 
netic Tape Adapter Unit (TAU). 
Abstract: Automatic map compilation using digital techniques is progressing 
at IBM in Kingston, N. Y. These advances represent over four years of re 
search and development, supported primarily by the United States Army, 
GIMRADA, Ft. Belvoir, Va., and IBM. Other agencies have supplemented 
this effort in collateral application areas. 
Experimental systems have been developed that are capable of digitizing and 
processing photographic data of various quality levels, ranging from TV-satel 
lite, X-ray, and radar-camera quality to that obtained with aerial-reconnais 
sance and precision-mapping cameras. Up to one hundred million bits of 
digitizable data are scanned from a stereo photo and recorded on magnetic 
tapes for data processing purposes. 
In the digital map compilation system, data associated with a pair of aerial 
photographs are simultaneously digitized. The most important data of this 
type are those concerned with control, obtained from ground-control surveys, 
and related measurements made on an experimental photo-digitizing stereo 
comparator; and other digitized data required consists of flight data, lens data, 
and other instrument calibration measurements. This digitized photo and con 
trol measurement data are recorded on tape for processing with a computer. 
Although these operations are basically automated, human skill is required 
for the stereoscopic identification and precise measurement of diapositive con 
trol points. In addition, the final editing of maps to conform to topographic 
practice requires the skill of expert cartographers. 
A series of systems test procedures was 
generated to perform an evaluation of both 
the DAMC sequential and predictive systems. 
The procedures, either in the form of a meas 
urement or a computer program, measured 
the effects of each process of the compilation 
system and the total system capability of 
producing contour manuscripts. Test proce 
dures were developed to: 
Compute the C-factor (vertical accuracy). 
Compute horizontal accuracies. 
Measure residual y-parallax in rectified 
photographs. 
Compute the spot placement error in the 
scanner with computer-generated grids. 
Verify the rectification process with digital 
checks. 
Measure operating time. 
2. DAMC scanner-printer combined with 
a WILD STK-1 stereocomparator. 
The tape units serve as storage media for 
computer input and output data. The TAU, 
in addition to serving as an interface, pro 
vides timing pulses and synchronization 
logic for the entire system. The scanner- 
printer unit has two functions: 
1. To convert photographic image infor- 
ihation to digital information in stand 
ard IBM tape format (accomplished in 
the Scan Mode). 
2. To convert digital data stored on mag 
netic tape to photographic image in 
formation (accomplished in the Record, 
i.e., Print Mode). 
Since the quality of maps compiled by the