INDIA 2
Company Private Ltd., Dum Dum, Calcutta. The aerial photographic tasks carried out by these two
agencies during the years 1960 to 1964 are given in Table 1 below.
Table 1.—Aerial photography in India during 1960-64
Camera & Focal
length
Scale
Area in
sq. km
Remarks
A. Indian Air Force
Eagle IX ( 6" )
Eagle IX ( 6" )
Eagle IX ( 12" )
Eagle IX ( 6" )
RC 5(a) ( 11-5 cm )
RC 5( a ) ( 11-5 cm)
RC 5(a) ( 21-0 cm )
RC 5( a) ( 11*5 cm )
Up to 1 : 10,000
From 1 : 10,000 to
1 : 30,000
From 1 : 10,000 to
1 : 30,000
Smaller than 1 : 30,000
Up to 1 : 10,000
From l : 10,000 to
1 : 30,000
From 1 : 10,000 to
1 : 30,000
Smaller than 1: 30,000
985
81,499
9,707
3,63,305
62
6,232
1,114
94,214
B. M/s. Air Survey
Company.
Eagle IX ( 6" )
RC 5( a ) ( 11 • 5 cm ) &
RC 8 ( 11-5 cm )
f Up to 2" — 1 mile
Smaller
4 than 2" = 1 mile
About 4" = 1 mile
On different scaies
1,51,524
1,00,895
174
48,417
So far, the above two agencies were able to meet the annual demands of aerial photographs
bv the different indentors in India. With the increased use of aerial photographs for topographical
mapping and photographic interpretation purposes, the demand of aerial photography has also gone
up considerably. A proposal for the expansion of the aerial photographic capacity of India is under
active consideration of the Planning Commission and action for acquiring some more precision aerial
cameras is in hand.
Timely and good quality aerial photographs are of great importance for the study and inventory
of natural resources. Both the Survey of India and the Indian Air Force departments are procuring
Log-Etronic dodger printers for ensuring better and uniform quality of photographic prints.
III. AERIAL TRIANGULATION
i. Radial triangulation.—The graphical method of radial triangulation for extension of plani
metrie control points, as experimented by Ho tine in the air survey of Arundel in 1926, was introduced
in the Survey of India by Capt. D. R. Crone during 1930-31, with modifications to suit Indian condi
tions. The experiment with modern air survey methods was greatly developed during the Second
World War ( 1939-45 ) and with the acquisition of slotted template equipment, the method of
mechanical radial triangulation for extension of planimetrie control was introduced in the Depart
ment. Since the Second World War, air photographs have been widely used in the Department, to
produce standard topographical maps as well as development project maps on scales ranging from
I : 5,000 to 1 : 50.000.
In the Department the method of principal point radial triangulation is mostly used for ex
tension of planimetrie control as the terrain so far surveyed by graphical air survey method is generally
flat or have gentle slope or minor undulations. Methods concerning extension of planimetrie control
in mountainous country are under development.