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found or he finds that it seemingly is not possible to do so.
In the latter case more ground information is needed either as a field check
if that is possible or by published reports and maps. In addition it would
probably be best also to consult with some one who has had more experience in
photogeology. In progressing further toward a correct terrain evaluation the
military photo interpreter should use such criteria as erosion features, tonal
qualities, land use and vegetation.
The previous discussion may indicate that in order to be a good photo-
geologist all that a military photo interpreter needs to be is a photo reader. This
of course is far from the truth, although he will very likely make use of photo
reading or recognition keys. He will also need to analyze the situation and
arrive at the correct answer by logical and deductive reasoning. Due to the
differential process of erosion, aggradation and the various deformations of the
earth’s surface very few if any regions of the earth will be exactly alike. For
this reason no key, unless it were prepared for a specific location, will give a
definite descriptive picture of the area. Certain items will be the same or
similar but with others, natural changes will have occurred which will present
a different view. It will therefore be necessary for the military photo inter-
preter to analyze properly the terrain condition and by inference or deductive
reasoning arise at the correct conclusion. The keys, regardless of how accurate
they are, will be beneficial only to a limited extent; from there on the ability
of the photo interpreter will be the crucial factor. The problem of vegetation
and terrain analysis is not a simple process of photo-reading or recognition as
is that, say for ship or plane identification. However with reliable terrain and
vegetation keys based on analogous areas and conditions, a well-trained military
photo interpreter can and probably will be called upon at various times to
prepare terrain estimation maps and reports. The accuracy of the end product
will of course depend upon the reliability of the keys as well as the deductive
reasoning of the interpreter.
With the recent developments in cameras, films and photo-reproduction
techniques the military photo interpreter must continually re-evaluate his
ability and limitations. Interpretation from negatives, positives and color
transparencies is becoming more important and as such the military photo
interpreter must keep up-to-date with the changes. He must be able to do
accurate interpretation from air photos of various scales and working condi-
tions. In order to help him with his duties, new types of stereoscopes, lighting
conditions, measuring devices, etc. are being developed, evaluated and eventu-
ally fabricated in sufficient quantities as to be available to all military photo
interpreters. With the development of reliable keys and new techniques, for
photo interpretation the Military Services are continually doing better and
more accurate photo interpretation of vegetation and terrain conditions. There
is still need however for improved methods for solving the many aspects of
this complex problem. Much improvement is being effected through research
within the Defense Department while additional help is coming from com-
merical companies and educational institutions.
