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EXPERIENCES WITH CONVERGENT PHOTOGRAPHY US.A-5 
except that we will always tend to accept what we consider the superior solu- 
tion for our purposes. Should a super wide-angle lens be produced which in our 
opinion performs satisfactorily as a lens, we will no doubt investigate its poten- 
tial as a component of a mapping system and made an impartial comparison 
with other existing systems to determine whether it fills a Corps of Engineers 
need. There are too many questions to be answered on'the use of a super wide- 
angle lens to permit one to arbitrarily state that such lens will make convergent 
photography obsolete. — i 
To summarize, we are faced with a problem not common perhaps in Europe 
but common enough throughout the rest of the world, the problem being to 
map large areas previously unmapped or mapped poorly, at medium scales with 
a high degree of accuracy and with a minimum amount of time and expense. 
To solve such a problem we are investigating the combination of high altitude 
flying and convergent wide-angle photography. Our laboratory studies clearly 
indicate that contouring accuracy can be improved by as much as 100 per cent 
if convergent photography with a base to height ratio of 1.2 is used in place of 
the conventional vertical photography with a base to height ratio of 0.6. Our 
aero-triangulation tests have not been conclusive as yet; however we feel we 
can say that aero-triangulation can be accomplished with convergent photog- 
raphy with no less accuracy than vertical photography, and possibly greater 
accuracy. We are at present continuing our investigations and hope to make 
our findings available to the photogrammetric world through papers prepared 
by our scientists and engineers, to the extent possible in keeping with our policy 
of not making direct comparisons of competitive commercial equipment. 
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