CAMOUFLAGE DETECTION BY INFRARED PHOTOGRAPHY
Camouflage is a protective device intended to confuse or deceive an enemy observer who may operate from the air or from ground observation posts. It may be accomplished by a number of methods, the chief of which are complete concealment, blending the object with its surroundings, disruption of the apparent form of the object, and deceiving by the use of dummies or making the object appear like something else. It is applied to such things as matériel, troops, military works, aircraft, ships of war, airfields, and industrial plants.4, 14, 15, 20, 21, 24, 28, 35
To be effective, camouflage must operate against direct visual observation and photography, particularly aerial photography. In a large number of cases, its purpose is to make the bombing of a specific target as difficult as possible. The bomb aimer is dependent on visual observation in using his sights, and the prime purpose of camouflage is to confuse him at the distance at which he must release his bombs to be effective. It is generally considered to be practically impossible to camouflage large installations in such a way that they will defy detection by photography from the air, and camouflage in such cases is carried out primarily for visual confusion. At the same time, it is certain that, if camouflage could be carried out to defy photographic observation as well, it would be worth while; much effort has been devoted to this objective. As the concealment becomes more effective, it becomes necessary to modify photographic methods of detection in order to cope with it.
The normal method of camouflage detection is to make what might be called "before and after" photographs, and in all cases to make overlapping pairs of pictures and examine them in the stereoscope. Interpreters have developed an uncanny sense for detecting details of objects in the stereoscope. To what extent