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REPORT OF COMMISSION VII 23 
airfield. This has led some authorities to the generalization that the ideal photo- 
interpreter might be a person who likes to crochet or knit or operate a calculat- 
ing machine, since patience, and little else, is required to do such repetitive jobs. 
However, for many other types of photo-interpretation far more than patience 
is required. For example, the proper professional background is of great im- 
portance to a photo-interpreter when attempting to extract information from 
the photos relative to problems in geology, forestry, engineering or warfare. 
Without such a background the interpreter may fail to interpret some features 
in their proper significance and may completely overlook other features having 
great importance. 
In still other types of photo-interpretation judgment may be a prime requi- 
site. This is especially true of problems requiring stratification of areas seen on 
the photographs into homogeneous units, as exemplified by Figure 1 in Brad- 
shaw's section of this Report. As indicated by the caption beneath this figure, 
the interpreter who wishes to draw stratification boundaries must simultaneous- 
ly judge the degree of homogeneity throughout the area photographed as re- 
gards at least five variables, realizing that a significant change in any one of 
the variables may require the drawing of additional stratification boundaries. 
Because changes in these variables often take place gradually, the interpreter 
frequently must decide where, within a rather broad transition zone, a change 
becomes significant. In addition, he must simultaneously keep in mind the con- 
cept that, when drawing any particular boundary, he must not subdivide the 
land into areas smaller than a specified minimum. This latter requirement 
necessitates still further judgment on the part of the interpreter in weighing the 
relative significance of various changes which he discerns in the five variables. 
With the increased emphasis currently being placed on photo-interpretation 
as a means of stratifying soil, plant life, animal life, and cultural features, judg- 
ment emerges as one of the prime requirements of the interpreter. In this con- 
nection, it may be that he recently has been done an injustice by certain of his 
critics; e.g., there are those who recognize that there are only two types of photo- 
interpretation—qualitative and quantitative. From this startling discovery, 
they hasten to the conclusions that (1) qualitative aspects of photo-interpretation 
merely entail leafing through existing photo-interpretation keys or other 
reference materials until an annotated example is found which matches the 
photo image in question, and (2) quantitative aspects are so simple and straight- 
forward that any high school student of average mathematical ability should 
experience no difficulty with them. While such an analysis may be valid for 
certain routine kinds of photo-interpretation, it overlooks completely the tech- 
niques required for certain other very important kinds, of which the afore- 
mentioned stratification problems constitute merely one example. As further 
examples it might be stated that, to the author's knowledge, there is neither 
a ready reference manual nor a suitable photogrammetric technique for answer- 
ing the following representative questions which he has been asked while serv- 
ing either as a military or civil photo-interpreter: (1) Has the enemy evacuated 
island *X"?; (2) Where, along this shoreline, is the best place to land tour 
infantry divisions abreast?; (3) How many people were killed at Hiroshima, 
based on these photos taken shortly after the atomic explosion?; (4) Where is 
the best place to locate our fire line so as to stop that forest fire?; (5) Where, 
within a radius of 50 miles of point "Y," is the most suitable site for develop- 
ment of a recreational area which will accommodate 100 boys? In answering 
such questions all the previously-listed major requirements of a good inter- 
preter must be brought to bear,—the critics notwithstanding.