human frailties with the additional prospect that operations,
not otherwise possible, may result. The incentive for auto-
mation is frequently technological curiosity and the search
for new knowledge. Photogrammetry is no different from other
fields in that the use of automation is basically dependent
upon economic factors. However, from a military standpoint
we cannot ignore the advantages, whether economically jus-
tified or not,in being able to produce maps in hours rather
than months in this era when a brush fire war may develop
overnight in several areas of the world. It is impossible
to be prepared with adequate maps to support military opera-
tions worldwide on short notice, especially when prior over-
flights in some areas, cannot be diplomatically arranged.
Compiling large scale maps is a very time-consuming operation,
and such map coverage as does exist becomes out of date in a
relatively short period of time. The potential of automation
for technologically accomplishing work which would otherwise
be impossible or economically unfeasible by man and his con-
ventional instruments is another significant factor. For
instance, because of the almost infinite number of corrections
that are possible through computer control, the potential for
a higher accuracy map product exists if adequate data are avail-
able through calibration or auxiliary information to provide
these corrections.
APPROACHES TO AUTOMATION
8. Approaches to automation of map compilation can be
grouped into three categories: (1) Modification of Conventional
Instruments, (2) Computer Controlled Plotters, and (3) All
Digital.
9. Historically, modification of conventional stereoplotters
was the initial approach to automation and is undoubtedly the
most easily understood by the general mapping community today.
In this approach the conventional, manually operated, projection
stereoplotter, such as the Kelsh, Nistri Photomapper, or Wild B-8,
is modified by the addition of electronic parts and circuitry so
that the photographic images on the diapositive plates are con-
verted into correlatable electronic waveforms. The correlation
logic circuits determine the direction and magnitude of any mis-
registration between the two homologous images and generate a
proportional error voltage to bring the images into registration.
This can be implemented either by (1) automatically raising or
lowering the tracing table in a manner similar to that which an
operator would do when viewing the floating mark or (2) fixing
the tracing table at the desired contour level and sampling the
correlation in such a manner as to determine the slope and direc-
tion of the contour line. The table is then driven to follow and
trace out the contour line.
10. The computer controlled plotters maintain proper relation-
ships between the photo coordinate system of the aerial cameras and
the map coordinate system through computer controlled mechanization
of the complex mathematical functions. The internal computations
are also used to control scale and to provide corrections for differ-
ential film shrinkage, lens distortion, earth curvature, refraction
