ral 
| be 
s in 
ven- 
for 
and 
e to 
the 
s of 
onal 
Geo- 
ling 
ular 
the 
hers 
vail- 
1ally 
o be 
irths 
oped 
luate 
ving 
and 
ian 
ation 
st al, 
nder- 
keys 
this 
NOW- 
ctive 
sions 
until 
ndeed 
vents. 
. The 
news- 
liged 
print. 
 non- 
  
PHOTO INTERPRETATION PICTURE, COLWELL 93 
military areas had been photographed from the air more than once. But as the earlier 
photography has become outdated new photographs have been flown in many of these 
areas to facilitate assessment of the current situation there. For example it is now 
federal policy to rephotograph most of the United States at intervals of no greater than 
ten years. As this repetitive cover becomes available, the photo interpreter is finding that 
  
Fig.1. An example of the best photography currently available of the 
surface of the Moon; on such photography interpreters are being asked to 
make detailed terrain analyses of a type that would have been considered 
quite irrelevant prior to the recent dawning of the Space Age. (Taken with 
a 200-inch reflecting telescope; courtesy of Mount Wilson and Mount Palo- 
mar Observatories, Calif.) 
by studying it sequentially he can derive such important information as the rate of en- 
croachment of urban developments on agricultural lands, the rate at which plant suc- 
cession or soil erosion occurs on a freshly disturbed area, and the extent to which changes 
in the timber volumes and species composition of a forest property are taking place as a 
result of logging, fire, or natural growth processes. 
c. In astronomy. At this Society's World Congress eight years ago, (or even four 
years ago), the days of satellite photogrammetry and photo interpretation still seemed 
quite remote to most of us. Since then some startlingly successful blast-offs have occur- 
red from launching pads in several parts of the world, causing us to look up from our 
stereoscopes long enough to ask what role the photo interpreter will be expected to play 
as a result of our newly found ability to place aerial cameras, and eventually even men, 
at stations in the heavens previously considered inaccessible. With the advent of this 
space age, photo interpreters are being asked to an ever-increasing extent to ferret out 
facts about the surface of the Moon and other heavenly bodies where man will soon wish 
to make “soft landings”. Some of this photo interpretation is being done from the excel- 
lent photography now becoming available from our large telescopes (Fig.1); some from