line with a Texas Instruments computer and
an operator's visual display. Data obtainable
are mainly digital terrain models, with other
uses such as transformations for terrestrial pho-
togrammetry and automated cartography.
Profiles and contours by epipolar scanning
At University College, London, work 1S
being conducted to produce profiles and con-
tours by epipolar scanning and off-line correla-
tion. A CP1 plotter is being modified to allow
for reading densities, simultaneously on both
photographs, on epipolar lines. The output on
magnetic tape also includes an x coordinate.
An IBM 360/65 computer is used for the corre-
lation (off-line) to compute heights along the
profiles. Further work, besides modification of
the CP1 plotter, consists of developing a system
to produce contours using the profiles thus ob-
tained.
Digitization of map data
With respect to automated photogrammetry
at governmental organizations, investigation is
continuing at the Ordnance Survey into the
feasibility of direct digitizing and filtering of
contour data on photogrammetric plotting ins-
truments. For existing maps, digitization is per-
formed on the original negative by Ferranti
Freescan digitizers (Gardiner-Hill, 1974). Only
points and not lines are digitized, and a cubic
spline is used to interpolate (in the computer)
about 8 times as many points. The reasons for
digitizing points are : (1) results are more accu-
rate ; (2) operation is less tiring to the opera-
tor ; (3) selecting points puts human skill into
an otherwise tedious job ; (4) combined point
digitizing and interpolation could be faster by
30 to 7o percent than line digitizing. The digi-
tized data are processed on the computer in the
following sequence: (a) conversion to core ;
(b) interpolation of additional points; and (c)
transformation to map-projection coordinate
system. A Xynetics flatbed plotter provides a
proof for editing before the final plot is pro-
duced.
UNITED STATES
Because of extensive American develop-
ments in automation of photogrammetry, this
part is divided into several categories : Depart-
ment of Defense, U.S. Geological Survey, U.S.
Forest ‘Service; State government agencies, and
universities and private firms. Some of the sys-
tems. described are basically automated carto-
graphy systems that include a major application
of automated. photogrammetry. Developments
in automated cartography that do not include a
significant element of automated photogram-
metry are omitted. Likewise, automated pro-
grams for adjustment of analytical aerotriangu-
lation are omitted, as these come within the
scope of Commission III.
Department of Defense
Advanced Automatic Compilation System
(AACS)
Intended to be an improved followon to the
Universal Automatic Map Compilation Equip-
ment (UNAMACE), the AACS (Mayer, 1974 ;
Madison, 1975) employs an all-electronic scan-
ning system in place of the mechanical x-y ta-
bles. Size of scanned area is flexible as are other
parameters, such as profile increment (y), step
increment (x), and x and y overlap and scan
rate (frequency). The input is a stereopair of
photographs, scanned and correlated ; the out-
put on magnetic tape consists of the resulting
X, V, Z coordinates. The tape is then used to
control a plotter for the production of con-
tours, or an optical printer for producing black-
and-white or color orthophotographs. This al-
lows for a variety of inputs and rapid produc-
tion of desired material, including digital in-
formation on the magnetic tape to be added to
a digital data bank.
Replacement of Photographic Imagery
Equipment (RPIE)
The major purpose of RPIE is to replace the
imagery of a low-resolution orthophoto with
imagery from high-resolution panoramic photo-
graphs. It will also be used for change detec-
tion and updating available photographs.
A modified AS-11B-1 viewer with two 9 -
x 18 - inch photocarriages positions and mea-
sures the input panoramic photographs by
using geometrically correct low-resolution or-
thophotos for control. The resulting measure
ments are used in an optical printer with a 9 -
X 18 - inch scanning stage to carry the high-re-
solution photo to produce the new orthophoto
on a 20 - X 40 - inch film drum. Simultaneous
measurement and orthophoto production is
normally done with two panoramic photo-
graphs under control of a PDP 11/45 computer.
