PHOTOGRAMMETRIC ENGINEERING 
10 
the tube face by manual or correlator control. 
Differential parallax detection is enhanced 
by a high-frequency X-axis wobble. The cor 
relation system senses the position of the scan 
pattern, height error, slope vector and in 
formation density and causes the scan pat 
tern to locate and follow any contour that 
exists within the model area imaged on the 
scanner. 
Operation of the AP-14 consists of setting 
the tube at a specified elevation in the model. 
The instrument is then in the search mode 
and the rosette scan performs a prepro 
grammed search until the cross-correlation 
voltage in the correlator exceeds a preset 
level, indicating image coincidence in the 
photomultiplier. At this point, when a con 
tour is intercepted, the search mode is auto 
matically interrupted and the contour 
following mode activated. The contour is 
automatically traced to the edges of the tube 
face and the search mode is resumed until all 
contours at this elevation on the area of the 
tube face have been completed. The beam of 
a display cathode ray tube moves in syn 
chronism with the DC position of the scanner 
beam’s center and is photographed by a copy 
camera to produce a contour manuscript. 
Contour printing speeds of from 5 to 15 
inches per second and C-factors in excess of 
500 have been attained in areas of moderate 
detail and slope. Contours are detected and 
traced in areas having slopes between 6 and 
60 degrees. The configuration of this instru 
ment represents a successful attempt to de 
vise a system not limited in its plotting speed 
by the mechanical inertia of a tracing table. 
In the present instrument, the tube face 
covers only part of the neat model area and 
must be indexed to adjacent positions. To 
realize its full potential either sufficient res 
olution must be realized to reduce the stereo 
model to the size of the tube face or a much 
larger tube face area must be constructed. 
Nonetheless this approach, which is basically 
analog utilizing electron-beam servoing tech 
niques, does not require a computer for con 
trol and posseses the capability of contouring 
a stereomodel within minutes. 
Universal Automatic Map 
Compilation Equipment 
The AP-14 and the previously discussed 
B8-Stereomat obtain their terrain data from 
projected stereomodels. Another class of 
automatic stereocompilation instruments, as 
represented by the system being developed 
for the analytical plotter, utilizes basically a 
stereometer for terrain data pickup and 
makes all necessary corrections by means of 
computers. Such a system was first success 
fully demonstrated in the Automatic Map 
Compilation System, shown in Figure 7. An 
orthophotograph and line-drop chart pro 
duced by this system are shown in Figure 8. 
Based on the principles developed in that 
prototype equipment follow-on instruments 
are being constructed for production use and 
are described by Dr. Sidney Bertram of The 
Bunker-Ramo Corporation, Canoga Park, in 
his paper, “The Universal Automatic Map 
Compilation Equipment.” 
The Universal Automatic Map Compila 
tion Equipment (UAMCE) consists of four 
identical scanning tables, a control console, 
a digital computer with input/output equip 
ment and associated electronics. The equip 
ment will serve for the automatic compila 
tion of accurate orthophotos and altitude 
charts or as a precision comparator. The 
great flexibility realized is obtained by use of 
the four identical scanning tables, any one of 
which can be used to carry a diapositive dur 
ing compilation or comparator operations or 
a film sheet for exposure of the orthophoto or 
altitude chart during compilation. Since the 
computer serves to center synchronous elec 
tronic scans on small conjugate areas of a 
stereopair of photographs, the separate scan 
ning tables for each diapositive allow almost 
any geometrical relationship to exist between 
the imagery on the two diapositives, provided 
only that the basic relationships are known 
and programmed in the computer. The basic 
relationship between conjugate areas in the 
two diapositives is a function of the basic 
geometry of the sensor modified by exposure 
orientation, second order effects and terrain 
relief. If all but terrain relief are programmed 
in the computer, the two electronic scans will 
be driven to nearly conjugate positions on the 
diapositives; and it will be the function of the 
correlator to detect and determine the re 
maining parallax and thus the relief. The 
Automatic Map Compilation System was 
built for nearly vertical photographs. In it 
the two inputs and the two outputs were con 
strained to the same scanning table permit 
ting only slight variations from parallel 
scans. However, with separate scanning 
tables in the UAMCE, sensor geometry is no 
limitation. Moreover, the system is not even 
limited to a point projection system and, de 
pending on the image quality, can be used 
equally as well with radar presentations.