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INTRODI 
The tre 
last few y 
have influe 
metry app 
developed 
gational pu 
new instri 
photogram 
of establis 
point of €: 
at the mor 
responding 
Shoran : 
give the 
radar altim 
records th« 
the grounc 
It is ev 
independer 
in conduct 
sible areas. 
electronic 
field for d 
extending 
mapping at 
metrist to « 
aerotriangu