INDIA 2
From October 1955 to September 1959 the particulars of Aerial Photography carried out,
cameras used, etc., are as under :—
Area covered with
Photography | . . Cameras used | Scale REMARKS |
| — |
3,00,000 sq. miles | (a) RC ba, 1 : 5,000 to
| (à) Eagle IX 1 : 50,000
( 7,77,000 Km? )
So far no attempt has been made to experiment with convergent photography and only vertical
photography has been used.
Areas Compiled.
During the period under report the areas compiled are :—
Large and medium scales .. 1,600 Km? ( Approx. )
Small scales .. .. 5,000 Km? ( Approx. )
Large scale mapping has been confined to small areas for special purposes and largest scales
on which mapping by Photogrammetric means has been carried out is on scale 1 : 1,000 using 1 : 6,000
scale negatives.
Further details are given below :—
Scale of Survey Area Surveyed
64" to 1 mile 746 Acres
16" to 1 mile 3454 ,,
12" to 1 mile 2030 ,,
6230 ,, = 9-7 sq. miles
6” to 1 mile 139-0 sq. miles
4" to 1 mile 163-0 3
3" to 1 mile 400-0 >
1 : 20,000 45-0 ;
1 : 25,000 964-0 E
1 : 50,000 816-0
9)
2536-7 sq. miles
or 6570-0 Km?
Control. —Plotting for details and contours is carried out using control provided by Aerial
Triangulation for small and medium scales. For large scales, accuracy required generally necessitates
fixation of complete control by ground methods. Plan controlis provided by Theodolite Triangulation
and Traversing and vertical control is based either on trigonometrical or on level heights depending |
upon the terrain and the contour interval.
Wild A 7 has been employed on supplementary control for surveys like 1 : 10,000, 1 : 25,000
and 1 : 50,000 and plottings of the order of 1 : 1,000 scale with contours at 2 ft. vertical intervals.
Wild A8 has been employed for plotting on scales like 1: 4,000, 1: 5,000, 1: 10,000 and
1 : 15,000 with contours at 5 and 10 ft. vertical intervals.
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