Serial m o j Area in Seale of | Contour Scale of Instrument 
No. Type of Survey sq km Map interval Photo- used Remarks 
graphy 
1 Basic National 8,600 1 : 50,000 40 m 1 : 30,000 B8/Stereotop 
Topographical to 
Mapping 1 : 60,000 
2 Basic National 1,92,900 1 : 50,000 10 or 1 : 40,000 A8/B8/Stereotop 
Topographical 20 m to 
Mapping 1 : 60,000 
3 Basic National 4,330 1 : 50,000 50 ft. 1 : 40,000 A8/B8/Stereotop 
Topographical to 
Mapping 1 : 50,000 
4 Basic National 32,000 1: 25,000 | 10/20 m 1 : 25,000 A8/B8 
Topographical to 
Mapping 1 : 60,000 
5 Special Project 2,800 | : 25,000 | 1 ft./1 m ] : 25,000 A7/A8 : Contours were based 
Surveys and on  spirit-levelled 
1: 42,000 heights. 
6 | Special Project 3,000 1: 20,000 |5 m & 10m] 1 : 20,000 
Surveys and 
1 : 50,000 
  
  
  
  
7 City Surveys for new 700 1:10,000 | Im/2:5m 1:10,000 
development and and 
] : 15,000 1 : 40,000 
8 Cadastral Surveys 70 1 : 1,000 1 : 6,000 
9 Assessment of depo- 225 1 : 5,000 5m 1: 60,000 A7/B8 The smaller scale 
sits of iron ore and photography was 
1 : 15,000 used for extension 
of control for map- 
| ping from the larger 
| scale. 
10 Various Construc- 250 | | : 5,000 1m/5 m | : 10,000 + This job was under- 
| tion projects | | to taken for construc- 
| | | : 25,000 tion projects like 
| | Steel Plants, etc. 
11 | Extension of 23 acres 1 : 500 Im | 1:10,000 A" Contours based on 
  
| National Training 
| | spirit-levelling. 
Centre for the Blind | 
  
  
  
  
The basic mapping subordinate organisations in the Survey of India are known as Parties. 
A large majority of these are field Parties charged with the responsibility of providing necessary 
ground control, verification of aerial photographs for identification of various cultural, develop- 
mental and other planimetric details and for provision of heights in relatively flat areas to 
points marked on the photographs. These field Units also carry out (¢) ground verification 
of photogrammetrically surveyed compilations ; (7) contouring in flat areas on these verified 
compilations using methods of plane-table survey and/or (2: ) air survey compilation by the 
oraphical ( Arundel method ) for subsequent verification and contouring in the field. Some 
of these field Units are provided with third order plotting machines for mapping at topographi- 
cal scales. The trigonometrical control for these third order machines is provided either in 
the field or by extension on precision Autographs. 
The field data are fed to the photogrammetrie Units located at various places. The 
photogrammetric Units carry out complete plotting of detail and contours and inking of the 
compiled manuscripts. These inked manuscripts along with guides for different colours and 
classification of detail are sent back to the field Units for necessary action regarding fair 
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