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sible to take measurements. This applies to both single photos, and, especially, 
to stereo-photographs. Thus, it is perfectly natural that photos are being more 
and more used for military purposes. 
Technics have placed photographic and photogrammetric methods at our 
disposal, which allow us to take photographs showing various circumstances of 
reproduction and making possible the taking of exact measurements. 
The black and white picture, taken with normal panchromatic emulsion, 
is still the one most used, but color film is gaining more and more ground for 
  
Fig. 1. Both amateur cameras as well as specially constructed cameras are 
used in the Army ground photo reconnaisance service. 
certain special tasks. Infrared photography also has its given field of use for 
taking photos through haze, and when photographing in order to pentrate cam- 
ouflage. Special two-layer emulsions, so called “CD”, making invisible shades 
of color distinguishable to the naked eye, are especially suitable for penetrating 
camouflage through the means of photography. Stereo-photography allows the 
third dimension to appear in an exaggerated way, clearly setting off the differ- 
ences in height in the terrain. Modern stereo-projectors with polarized light 
make it possible to show stereo-pictures to large audiences. Stereo-measuring 
instruments allow the measuring of all three dimensions with an accuracy which 
is dependent on the construction of the cameras and on the instruments used in 
analysing. Great focal lengths cause distant objects to be reproduced in large 
scale. With certain types of cameras, the finished, positive prints, may be had 
in as short a time as one minute after exposure. An example of cameras used 
in ground photo reconnaissance is shown in fig. 1. 
The great scope of the technique of photography, must, however, be used 
with discernment. The best results are often achieved with a simple technique. 
This is especially the case when first class photographic personnel are not 
available. 
Some of the fields, where ground photography is of importance to ground 
operations, are touched on briefly in the following report. 
I. GROUND PHOTO RECONNAISSANCE. 
Principles. 
The human brain does not work objectively during excitement such as when 
      
    
  
  
  
   
  
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