PHOTOGRAMMETRIC ENGINEERING 
2. The physical location of the effort; where should the interpreter interpret? 
3. The nature of the intelligence environment in which the tactical interpreter 
operates. 
4. Psychological factors differentiating tactical interpretation from other types. 
5. How should tactical photo interpreters be chosen; should the requirements be 
different because of tactical demands? 
Tactical interpretation is bound by the photographic process far more than 
is appreciated by strategic interpreters or experts on urban analysis. Limitations 
begin when the photo plane takes off on a mission. It takes time, a minimum of 
time, it is true, to actually take the pictures and return to the airfield. Much 
more time to make the prints. Meanwhile the newly photographed machine gun 
position has been manned and has picked off two men on patrol. The airfield, 
of course, is not on the front lines or even close to it, so it takes more time to 
transport the photographs (by now a very bulky package) to the interpreter. 
How much time is lost? There are too many variables to permit even an approxi- 
mation of the average lag from the moment of exposure to the finished print 
under the interpreter's stereoscope. But as a working supposition it might be 
held that if the photographs were taken at ten in the morning, interpretation 
might begin at five or six in the evening. ; ; 
This in turn leads to a number of tactical working habits. For instance, when 
there is only minor movement on the front, the value of photographic intelli- 
gence far outweighs the disadvantage of a time lag. But when the battle is hot, 
when. the main line of resistance is moving rapidly, when it is fluid and wildly 
fluctuating, it takes too long to obtain the photos and squeeze the intelligence 
from them for the information to be trustworthy at the moment of report. 
There is a middle ground; good technique and efficient organization compress 
the time lag, so that photo intelligence retains its utility even when the situation 
becomes more and more fluid. But as a generalization it might be said that the 
real use of photo intelligence is before and between attacks, not during them. In 
a rapid advance, photo intelligence is not the most useful tactical information 
available. 
This means that the tactical interpreter experiences cycles of feast and 
famine. When the front is fluid his interpretation activities are negligible. When 
it is static, they are overwhelming. 
Now one way to shorten the time lag immediately comes to mind; why not 
let the interpreter do his work at the airfield where the photo plane lands? Why, 
in fact, should he do it anywhere else? 
Let the nature of the tactical situation make the decision. For instance, it is 
much more effective if the interpreter personally assists in the briefing of a patrol 
than if a written report is all that is available. Writing a report, even a sketchy 
one, might in fact entail enough delay to counterbalance the gain made by 
stationing the interpreter at the airfield. So that if delay must occur either in 
delivery of the photographs or in delivery of the information, which is the least 
worst? Of the two, it is far better to deliver the photographs rather than the 
information. 
The case for delivering the photos is made stronger by this fact: if the in- 
formation is delivered, instead of the photos, the intelligence is derived by an 
interpreter far removed from the front. Not ónly is this inconsistent with good 
practice, but front line troops are usually suspicious of tactical decisions made 
in rear areas. Even if delivery of the actual photos takes much longer than the 
messaged information, the photos themselves are infinitely more useful. 
In addition, the photos themselves are needed quickly by many people in