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PHOTOGRAMMETRIC ENGINEERING 25 
of large areas in a minimum of time and the 
rapid compilation of aeronautical charts at 
medium and small scales. The speed by 
which aerial photography was obtained is 
demonstrated by the fact that, using the 
trimetrogon method, more than 15 million 
square miles of the earth’s surface were 
photographed during the war years. Dur- 
ing the past ten years improvements in the 
original trimetrogon compilation tech- 
niques have been made by the Aeronau- 
tical Chart and Information Service, the 
Geological Survey, and the USAF Wright 
Air Development Center. 
In April 1943 the Aeronautical Chart 
Plant was established in St. Louis, Mis- 
souri, as the primary operating facility of 
the Aeronautical Chart and Information 
Service. An original complement of 60 
photogrammetrists has been expanded to 
almost 400 personnel. This personnel is 
engaged in producing the many different 
types of maps, charts and aerial photo- 
graphic mosaics required by the USAF for 
operations, intelligence studies and train- 
ing. 
Photogrammetric compilation for small- 
scale charting is generally accomplished 
by the trimetrogon system, obtaining spot 
elevations and contours by the use of the 
Wilson photoalidade. However, Air Force 
requirements for larger scale charts and 
more detailed topographic information 
caused the Aeronautical Chart and Infor- 
mation Service to include stereophoto- 
grammetric compilation. Since 1948, me- 
dium and large scale compilations were 
produced by use of several different types 
of stereo plotters, such as the Kelsh, 
Mahan, KEK, and a Stereoplanigraph. 
Aerial photographic mosaics are produced 
from all types of oblique and vertical 
photography. The equipment used for 
this work includes Bausch and Lomb, 
Saltzman, Zeiss, and Fairchild rectifying 
projection printers. 
The Photogrammetry Section of Aero- 
nautical Chart and Information Service 
has contributed extensively in establishing 
requirements for new equipment, recom- 
mending modifications to improve existing 
equipment, and developing new compila- 
tion procedures. 
Plans and programs of the Aeronautical 
Chart and Information Service have been 
the successive responsibilities of W. T. 
Reagan, Robert H. Kingsley, Sidney E. 
Tischler and Benjamin B. Lane, Jr. 
Direction of the activities in St. Louis was 
carried on by Major R. O. Davis during 
World War II, and now by Major Robert 
D. Dixon. 
U. S. Navy HvypROGRAPHIC OFFICE 
Immediately after World War I, the 
U. S. Navy Hydrographic Office recog- 
nized the potential utility of aerial photo- 
graphs in connection with hydrographic 
surveys. In 1922 aerial photographs were 
obtained and used in a planned and sys- 
tematic manner and since then they have 
become an integral part of all hydro- 
graphic surveys. 
During the early years, aerial photo- 
graphs were used for field reconnaissance 
and determination of the shape and extent 
of shoreline, reefs, and shoals. Photographic 
flights were planned to follow the coast- 
line, but there were no particular require- 
ments concerning stereoscopic overlap or 
excessive tilt. Actual placement of hydro- 
graphic features was accomplished by con- 
ventional field survey methods. 
In 1933 the Bureau of Aeronautics, De- 
partment of the Navy, adopted the T-3A 
five-lens aerial camera; the acceptance of 
this camera was paralleled by the estab- 
lishment of a Photogrammetry Unit in 
the Hydrographic Office. In 1934, five-lens 
aerial photographs supplemented by speci- 
fication vertical photography were ob- 
tained of the Aleutians, Costa Rica, and 
Panama. Standardized photogrammetric 
plotting methods were adopted and de- 
veloped, and aerial photographic specifi- 
cations concerning overlap, tilt, and qual- 
ity were established. 
Early photogrammetric plotting meth- 
ods were of the radial line type and were 
concerned primarily with interpretation 
and placement of shoreline, off-shore fea- 
tures, prominent land marks, and plani- 
metric detail. Spot elevations were deter- 
mined by parallax bar readings. The 
"Annual Report of the Hydrographic 
Office" for 1934 also notes a continuing 
"study of various aerocartograph ma- 
chines.”