If it should now be impossible, because of the limitations of the A 7 Autograph, 
to make an absolute orientation of ¢' and ¢, " the plotting of the building must be 
performed as shown in Figure 3, also of Congress Hall in Philadelphia. Plotting is 
in both plan and elevation. It is part of the usefulness of the A 7 Autograph for 
architectural photogrammetry that a change of the gear system, from "aerial, '" with 
which architectural elevations are plotted, to "terrestrial, " with which architectural 
floor and ceiling plans and horizontal sections are plotted, also provides correction 
of plotting distortions of common architectural cylindrical forms, as described in 
"Architectural Photogrammetry at Ohio State University" in the December,1957 issue 
of Photogrammetric Engineering. 
The resulting plottings, which require the plan drawing for the rotation of the 
foreshortened elevations into full frontal projection, as shown in Figure 4, provide 
the best determination of inaccessible dimensions on the buildings, necessary for the 
final drawings and for the control of plotting of more nearly frontal stereopairs. 
A comparison of vertical dimensions of the inaccessible tower of Saint Paul's 
Chapel on Lower Broadway in New York City, shown in Figure 5 - as determined 
from various diagonal stereopairs of the building and before full development of the 
system of survey control and orientation described herein - indicated an accuracy to 
within 1 part in 1300 on the height of the tower. This degree of accuracy is satisfactory 
for the recording of historic architecture. Other applications of photogrammetry to 
architecture can utilize the ultimate degree of accuracy possible with the science of 
photogrammetry. 
Pr A bo dle a ia 
  
  
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