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.