CONVERGENT PHOTOGRAPHY! 
    
   
By 
Wiliam A. Radlinski 
| In the continuing search for greater € 
| topographic maps from aerial photographs i 
basis of the photogrammetric operation, n 
vertical photograph is, of course, the mos 
ve been refined to a point where maximum utilization of 
y is being approached. Unless aerial camera lenses of. 
ular coverage are made available in the very near future, 
signed for verticals ha 
this type of photograph 
substantially wider ang 
and this does not appear likely, 
photogrammetric mapping methods mus 
Photogrammetric Engineer 
U. S. Geological Survey 
conomy and efficiency in making 
t may be well to reconsider the very 
amely the aerial photograph. The 
t widely used today. Instruments de- 
the answer to the problem of more efficient 
t be found elsewhere. Such an answer 
may be found in convergent photography. 
  
Fig. 1. Camera couple for convergent photography. 
As used in this paper, th 
with a simple twin-camera arrangement consis 
cision aerial cameras coupled rigidly together so 
axes lie in a common plane and form an ang 
The shutters are synchronized so that simultaneous 
with each other (Fig. 1). 
exposures are made with both cameras O 
are taken so that the coverage 
sure station overlaps the coverage 0 
next exposure station by 100 percent, 
ht (base-height ratio) is 1.28. The comparable 
exposures to the flying heigl 
Presented at the Seventh Congress O 
grammetry, September 6, 1952. 
e term "convergent" defines photography taken 
ting of a pair of wide-angle pre- 
that their respective optical 
le of 20? with à plumb line and 40? 
f the coupled pair. When exposures 
of the forward-looking camera from one expo- 
f the backward-looking camera from the 
the effective ratio of the base between 
f the International Society of Photo-