in driven
| the pro-
rgements.
tt incan-
e for han-
y selected
strument,
ed for in-
van type
and is 74
st travel.
res on a
Im by the
lata have
value in
has speci-
7 projects
al photog-
triangula-
ereoplani-
tes for all
ers on the
raphically
ment co-
y coordi-
ques, but
pplied on
me U. S.
tted tem-
Multiplex
ip Service
ethod. In
1odels are
e approx-
€ plotted
these are
Multiplex
in a con-
to deter-
complete
1e United
rmy Map
1947, now
pile maps
wherever
> is non-
andpoint,
1 altitude
mmercial
y 315,000
lepartment
square miles of this special photography
has been acquired. The Army Map Serv-
ice has encouraged the use of high alti-
tude photography and has pioneered in the
use of this photography for medium-scale
stereocompilation.4
g. Where the method may be applied
advantageously, the Army Map Service
has since 1947, employed dual flight alti-
tudes for the same project area. In this
technique, the higher altitude photog-
raphy is utilized for horizontal control ex-
tension through aerial triangulation, and
the lower altitude photography on which
the established photogrammetric control
is identified, is used in conventional com-
pilation. This procedure reduces costly
field work without a sacrifice in accuracy.
h. Army Map Service continued the
practice followed by the military services
during the past war, of using large-scale
photography for intensification of detail
being compiled from smaller scale mapping
photography. 'This larger scale supple-
mentary photography is taken simultane-
ously with the mapping photography. In
1951, for the first time, due to an Army
Map Service procurement specification,
a civilian firm in the United States made an
installation of this type to fulfill the stated
requirements.
i. Beginning in 1939, the Corps of En-
gineers, through its District Offices, ini-
tiated the requirement for performance
testing of aerial cameras.’ This system pro-
vided for flying the aerial cameras over
a fully-controlled area and setting stereo-
scopic models to check the resulting ac-
curacy when used under actual operating
conditions. This testing was performed
prior to each photographic project and
periodically thereafter as required. Since
1946, Army Map Service has elaborated
this testing so that camera performance is
now checked by laboratory calibration,
flight perfomance testing over controlled
areas, and inspection of every roll of proj-
ect film for distortion within a short time
after exposure and development. The last
part of the testing is made by setting check
stereo models.
RELATED CONTRIBUTIONS TO THE PHOTO-
GRAMMETRIC FIELD
These contributions are:
a. The Corps of Engineers has, since
PHOTOGRAMMETRIC ENGINEERING 21
1939, used a "'classification survey" system
of collecting cultural information such as
place names, road classification and simi-
lar data, in advance of the map compila-
tion process. This information which is
secured in the field, is annotated on the
aerial photographs for subsequent office
use.
b. In 1948 the Army Map Service
Geodetic Division established an extensive
controlled area for testing aerial photo-
graphic equipment and photogrammetric
mapping methods.® This area has individ-
ual horizontal and vertical picture con-
trol points as well as combined control
points spaced at measured intervals. The
points are all photo-indentifiable, either
through construction on the ground or be-
cause of their natural or structural char-
acteristics and location. The control in this
area is being maintained and is inspected
and serviced at biennial periods to insure
its availability for its intended purpose.
BIBLIOGRAPHY
1. “The A.M.S. Method of Tilt Analysis,”
A.M.S. Bulletin No. 12, C. of E., Dept. of
the Army, Washington, D. C., Oct. 1944.
2. “Notes on the A.M.S. Method of Tilt
Analysis,” A.M.S. Bulletin No. 19, C. of E.,
Dept. of the Army, Washington, D. C.,
Aug. 1945.
3. Brandt, Robert S., “Discussion of Spatial
Triangulation with the Zeiss Stereoplani-
graph,” PHOTOGRAMMETRIC ENGINEERING,
Vol. XIV, No. 3, Sept. 1948.
, ‘Aerial Triangulation with the
Stereoplanigraph," PHOTOGRAMMETRIC EN-
GINEERING, Vol. XVI, No. 4, Sept. 1950.
, ‘Resume of Aerial Triangulation
Adjustment at the Army Map Service,”
PHOTOGRAMMETRIC ENGINEERING, Vol.
XVII, No. 5, Dec. 1951.
4. Dickerson, Lewis A., ''Use$ of High Altitude
Photography for Mapping and Reconnais-
2%
sance,' PHOTOGRAMMETRIC ENGINEERING,
Vol. XVI, No. 1, March 1950.
5. Webb, James P., “Performance Testing of
Aerial Cameras for Photogrammetric Map-
ping," PHOTOGRAMMETRIC ENGINEERING,
Vol. XVIII, No. 1, Mar. 1952.
. Hopkins, Page, ‘Establishing Control for
Aerial Mapping Test Area in Southern
Arizona," Surveying and Mapping, July-
Sept. 1951.