determine which of these requirements might be met and by what 
remote sensing process. 
If either of these two approaches were to be used, however, consid- 
eration would eventually need to be given to the best compromise 
between user requirements and remote sensing capabilities. For 
example, if under the second approach, it were found that one of 
the desired items of information could not be directly obtained 
by means of remote sensing, the investigator should consider 
whether the requirement might be so modified as to make acceptable 
to the user some alternate kind of information which could, indeed, 
be derived through the remote sensing process. 
As indicated by Figure 4*it is sometimes helpful to consider that 
there are several links comprising the chain of events by means 
of which remote sensing techniques can be used to satisfy the 
information requirements of various resource management groups. 
On the one hand, the "hardware oriented" person is likely to use 
the first of the two approaches, viewing the matter as proceeding 
from the left links of the chain forward and to the right. On the 
other hand, the "management and policy" oriented person is likely 
to use the second approach. 
*Figure 4 is not reproduced here. 
Summary and Conclusion 
This paper, in attempting to document progress in photo inter- 
pretation during the past 25 years, has highlighted the very 
substantial role played by Commission VII of the International 
Society for Photogrammetry in bringing about that progress. An 
analysis is given of the major specific factors that have in- 
fluenced that progress including (1) the impact of World War II's 
photo interpretation trainees; (2) efforts aimed at the systematic 
training of photo interpreters in the post-war era; (3) recent 
improvements in sensor platforms and sensor systems; and (4) recent 
improvements in capabilities for the analysis of remote sensing. 
Since much of this progress has resulted from the urgency,-on a 
worldwide basis, of our making better inventories of natural 
resources (with the use of remote sensing, in general, and photo 
interpretation, in particular) there is a central thread in this 
paper that relates to such use. 
The paper concludes with a substantial section that speculates on 
the probable future of remote sensing technology and training, with 
special emphasis on the future for both photo interpretation and 
photo interpreters. 
A primary objective throughout this paper has been to provide for 
photo interpretation, certain "retrospect" and "prospect" views 
of the types that are needed in most any fast-growing discipline. 
The man who most eloquently expressed need for such views was an 
eminent American of more than a century ago, at the time when he 
was President of the United States. His name was Abraham Lincoln. 
President Lincoln said, although in a quite different context, 
of course, "If we better knew where we are and whither we are 
      
  
  
   
  
  
  
  
   
  
  
   
  
  
  
  
   
  
  
  
  
  
  
   
   
  
  
  
  
  
   
  
  
   
  
   
  
  
  
  
  
     
    
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