22 REPORT OF COMMISSION VII 
coming World Congress. Abstracts of several of these papers are published else- 
where in this issue. 
In concluding this section on photo-interpretation equipment, materials 
and methods the following points seem worthy of emphasis: 
(1) The equipment, materials and methods currently in use by photo- 
interpreters are adequate for meeting certain minimum requirements. This 
is not surprising in view of the fact that the requirements to be met by the 
photo-interpreter usually are formulated on the basis of a preliminary study 
as to the information which he ordinarily can derive from the photos. However, 
if certain improvements were made, much additional information of value might 
be extracted and the ease and accuracy of photo-interpretation might be greatly 
increased. 
(2) There is need for improvement in such basic items of photo-interpreta- 
tion equipment as stereoscopes, magnifiers, light sources and measuring devices. 
(3) There is need for the development of a photographic print material which 
will better preserve the inherent photographic detail, will receive pencil and ink 
annotation, will permit erasures, and will resist curling or cracking of the emul- 
sion when rain-soaked or otherwise abused under rugged field conditions. 
(4) There is need for improved techniques that the photo-interpreter can 
employ in systematically searching photography so that each area will be 
thoroughly studied once, and once only. 
DESIRABLE CHARACTERISTICS OF THE PHOTOGRAPHIC INTERPRETER 
Recently considerable thought has been given as to how the human link 
in the photographic reconnaissance-interpretation chain might be improved. 
An excellent article relative to this subject is that of Reyna (1952). In it 
the various ways for improving this link are discussed under three major head- 
ings, (1) criteria for the selection of photo-interpreters, in accordance with the 
skills, aptitudes, personality traits and experience pertinent to the task, (2) 
techniques for their training and (3) devices and viewing conditions for aiding 
the interpreter in his task. Reyna recommends as a fourth area of study, the 
identification of the various perceptual factors which are revealed when (1) 
the photo technique is held constant and the detail varied and (2) the detail 
is held constant and the photo technique varied. 
A second paper pertinent to this discussion is that of Aschenbrenner (1952) 
in which it is emphasized that the interpreter must know the laws of stereoscopic 
space and form distortion in order to interpret tridimensional form correctly 
from stereo pictures. He points out that, because of inherent peculiarities in 
organization of the human sense of vision, a photo-interpreter cannot see an 
ordinary metrogon stero pair of photos without depth exaggeration, no matter 
what kind of stereoscope he may use. 
One of the most encouraging recent developments in the field of photo- 
interpretation lies in the fact that, as indicated above, the psychological and 
physical factors of the interpreter are finally coming under the careful scrutiny 
of experts. 
According to one listing, the major requirements of a good photo-interpreter 
are (1) acuity of vision, (2) powers of observation and imagination, (3) patience, 
(4) judgment, and (5) proper professional background. 'The relative importance 
of these requirements depends to a large degree upon the type of photo-inter- 
pretation being performed. For example, a great deal of patience and relatively 
little judgment is required of the photo-interpreter when counting the number 
of cars in a parking lot, ducks in a wintering ground, or bomb craters in an 
  
  
    
   
   
    
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
  
  
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