HISTORY OF PHOTOGRAMMETRY IN THE UNITED STATES 
TENNESSEE VALLEY AUTHORITY 
Shortly after the Tennessee Valley 
Authority was created in 1933, there was 
an immediate demand for topographic 
coverage of the Tennessee Valley water- 
shed, some 42,000 square miles in extent. 
Photogrammetry was in its infancy in 
America at that time, and such a large and 
immediate need for topographic coverage, 
cadastral surveys, land use studies, etc., 
created a demand for investigation into 
new ideas and processes. 
Realizing that topographic mapping of 
such an area through any method would 
take a number of years, the topographic 
program was temporarily postponed and 
the effort of the TVA’s mapping forces, 
with the cooperation of the U. S. Geolog- 
ical Survey, was directed toward prepara- 
tion of a 1:24,000 7i-minute quadrangle, 
planimetric series, of the entire Valley. This 
was produced in less than four years by 
means of 5-lens photography, controlled 
horizontally by basic triangulation and 
traverse, and radial line photogrammetric 
solution. This radial line work was one of 
the. early photogrammetric efforts in 
America. Compilation of this series was 
completed in 1936. 
Prior to this, a few Multiplex aero pro- 
jectors had been received by the Air Force 
at Wright Field for experimental purposes. 
In view of the success of the photogram- 
metric approach to the planimetric series, 
the possibilities of the Multiplex were im- 
mediately investigated by representatives 
of the Tennessee Valley Authority and the 
U. S. Geological Survey. A few bars of 
normal-angle equipment were acquired, 
and were installed in the offices of the 
Tennessee Valley Authority at Chatta- 
nooga. 
The topography obtained was thor- 
oughly checked; the results indicated that 
the Multiplex held possibilities as an eco- 
nomical means for producing maps of 
standard accuracy. The Tennessee Valley 
soon became the great proving ground of 
American photogrammetry. During the 
next few years, continual study and re- 
search, designed to isolate probable errors, 
was undertaken. It is believed that the 
TVA-USGS cooperative endeavor in Chat- 
tanooga can be credited with much of the 
development of the Multiplex as a pro- 
  
ductive and economical tool for the Ameri- 
can mapping profession. 
The research included the analysis of 
lens distortion and the design of a dia- 
positive printer to compensate for these 
distortions. Under the leadership of T. P. 
Pendleton and R. K. Bean much of the 
preliminary work leading to the American 
design of multiplex equipment was ac- 
complished during this cooperative pro- 
gram. 
During this time, R. O. Anderson, re- 
cently deceased, engaged in considerable 
research and developed a number of 
photogrammetric principles and formulas, 
the most notable of these being the scale- 
point method for tilt calculation of the 
aerial photograph. The Flynn Projection 
Plotter was developed by Abe T. Flynn 
for drawing map projection lines. The 
Photo Triangulator was constructed by 
the Branch in 1937. 
Since 1933 the Tennessee Valley Author- 
ity has made cadastral surveys of more 
than 2,000,000 acres of privately-owned 
property, representing some 40,000 indi- 
vidual ownerships in the Valley area. 
Aerial photography was used in practically 
all of these surveys. In the surveys of ap- 
proximately 1,500,000 acres enlarged ae- 
rial photographs were used as a planetable 
sheet in the field; on this cultural features 
which served as property lines and im- 
provements were identified and were later 
converted to true map position by radial 
line methods in the office. It is believed 
that this was the first large undertaking 
for which such a procedure was used for 
property surveys. Later, as the topo- 
graphic program of the Authority ad- 
vanced and Multiplex manuscripts at 
rather large scale were available on which 
fence lines, woods lines, hedgerows, 
streams, and other features likely to repre- 
sent property lines were shown, facsimile 
copies of the manuscript were made into 
planetable sheets and used as a base for 
property surveys. 
Tennessee Valley Authority Technical 
Report, No. 23, "Surveying, Mapping 
and Related Engineering," covers prac- 
tically all mapping activities of the Maps 
and Surveys Branch; it is just off the 
press. 
    
  
   
  
  
  
  
   
  
  
  
  
   
  
  
   
  
  
  
  
   
  
  
  
  
   
  
  
   
  
   
  
  
   
  
  
  
  
   
  
  
  
  
   
  
  
   
  
  
  
  
   
  
  
  
  
    
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