6 REPORT OF COMMISSION VII 
World War II for obtaining night photography consists of a condenser and two 
large light bulbs, with reflectors, mounted in the photographic aircraft and 
electrically connected with its power plant. The large amount of electrical 
energy stored up within this unit during the period between successive exposures 
is suddenly discharged through the light bulbs at the moment the camera shut- 
ter clicks, thereby illuminating the ground during the instant of photography. 
The question which some interpreters have asked is: ‘Might not this type of 
equipment be of potential value, not merely for taking photographs at night, 
but for increasing the amount of light reflected from shaded areas in daytime 
photography?" If so, photo-interpretation of such areas would be greatly facili- 
tated because of the added photographic detail discernible therein. For example, 
lack of detail in the shadows on conventional photography often makes it 
difficult for the photo-interpreter to delineate roads, trails and other planimetric 
features which may be discernible only intermittently as they wind beneath 
a canopy of trees; determination of types of soil or of understory vegetation in 
such areas is rendered difficult for the same reason. Lack of detail in shaded areas 
also renders topographic mapping of forest land by photogrammetric means very 
difficult in that the photogrammetrist may be unable to keep the floating dot of 
his stereoscopic plotting machine in apparent contact with the earth’s surface 
as seen on the model. Finally, lack of detail in shaded areas makes it difficult 
to see the ground at, or near, the base of a tree, building or other tall object. This 
impairs the photo-interpreter's ability to estimate heights, since all known meth- 
ods require an ability to see the ground at or near the base of the object. 
Because of the fact that light intensity diminishes as the square of the dis- 
tance from the light source, even the most powerful airborne photo flash units 
developed to date would be ineffective on a normally bright photographic day 
at altitudes greater than a few hundred feet. Even so, such photography might 
find widespread use judging from the enthusiasm recently expressed by various 
photo-interpreters for low altitude strip-sampling. Furthermore, photography 
taken at low sun angles or beaneath a dense overcast might show the effects of 
photo flash equipment from appreciably higher altitudes. 
D. OTHER AERIAL PHOTO RECONNAISSANCE EQUIPMENT: 
Several items of equipment currently being developed primarily with photo- 
grammetric considerations in mind are of great interest to photo-interpreters as 
well. Two such items are shoran and gyrostabilized camera mounts, the combina- 
tion of which may not only assure the photo-interpreter of obtaining more uni- 
form geometry in the stereo models and more uniform side lap between adjacent 
flight lines, but may greatly facilitate his plotting of significant objects in their 
true plan positions once he has interpreted them. Other items of equipment of 
perhaps even greater significance cannot be mentioned here due to security 
limitations. 
E. NON-AERIAL, PHOTOGRAPHIC EQUIPMENT AND MATERIALS: 
If we turn our consideration to non-aerial types of photographic equipment 
and materials, there are many other significant developments in recent years 
worthy of mention. These include: (1) underwater cameras, usable in depths of 
several thousand feet (Owen, 1951; U. S. Navy, 1951); (2) astronomic telescopes 
and cameras capable of photographing heavenly bodies at distances three times 
greater than was heretofore possible (Heyden, 1950); (3) electron photomicro- 
graphic equipment capable of magnifying objects 200,000 times and of rendering 
visible, for the first time, individual molecules only five atoms in diameter (Wyck- 
  
    
  
   
   
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
  
  
  
  
  
  
  
  
  
  
  
   
  
  
  
   
  
    
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