The Survey of India and modern mapping institutions

Detail

1. Survey of India: origin and first big map

• Survey of India (SoI): India's national mapping agency. It was set up in 1767.
• Its intensive topographical surveys (detailed surveys that measure land height, rivers, roads and settlements on the ground) began from that year.
• This work led to the map of Hindustan in 1785.

• The map is linked with James Rennell.

• 1767 is the start date. In that year Major James Rennell was made Surveyor General of Bengal, and SoI traces its origin to this post [3].

• It grew out of the work of East India Company surveyors. In the 18th century they explored land that no one had mapped yet [2].

2. Survey of India today

Feature	Fact
Status	Oldest scientific department of the Government of India [2][4]
Role	Principal mapping agency of the nation [2][4]
Headquarters	Dehradun, Uttarakhand (Hathibarkala Estate). The Surveyor General's Office works from here [2][4]
Parent body	Department of Science and Technology (DST), Ministry of Science and Technology [2]
Head	Surveyor General of India
Scales mapped	The whole country at 1:250,000, 1:50,000 and 1:25,000
Growth	5 Directorates in 1950 → 22 Directorates at present (SoI website, accessed 2026) [2]. An older DST page gives 18 [4]
Digital work	3 Digital Centres, set up in the late 1980s. They prepare Digital Topographical Databases for the whole country [2][4]
Training	National Institute for Geo-informatics Science & Technology (NIGST) [2]
Policy	Works under the National Geospatial Policy 2022 and the 2021 guidelines on geospatial data [2]

• Other duties of SoI [4]:
• It keeps the geodetic control network, the set of exactly fixed points on which all other maps are built.
• It sets the standard spelling of geographical names.
• It shows India's external boundaries on maps.
• It certifies how the boundary is drawn on maps printed by other agencies.
• It gives tide predictions for 44 ports.

3. Map series

• Map series: a set of maps made at the same scale, style and specifications. Their sheets fit together when placed side by side.
• So one large area, such as all of India, can be split into many small sheets that join without gaps.

• Example: the SoI toposheets (topographical sheets at 1:250,000, 1:50,000 and 1:25,000). Their numbering is covered in topographical-maps.

• National mapping organisations in every country make such series maps (Class 11, Ch 5).

4. Great Trigonometrical Survey (GTS)

• Triangulation: a way of fixing exact positions with a chain of triangles.
• First, a baseline (a straight line on flat ground) is measured very carefully.
• Next, angles to far-off hilltops are measured from each end of that line.
• Each new triangle uses one side of the triangle before it, so the chain spreads across the country.

• Result: exact positions and heights for thousands of points.

• Key facts about the GTS:

• Start: 1802, at Madras, by William Lambton.
• Main line: the Great Arc, a north–south chain of triangles along roughly the 78° E meridian, from South India towards the Himalaya.
• Continued by: George Everest (Surveyor General 1830–1843).

• Peak XV: around 1852, Radhanath Sikdar, an Indian mathematician and "computer" (a person who did survey calculations), worked out that Peak XV was the world's highest peak. It was named Mount Everest in 1865.

• Why it still matters: SoI says the GTS series that run north–south and east–west are "some of the best geodetic control series available in the world" [2][4].

5. The Pundits: secret mapping of Tibet

• Pundits: Indian surveyors trained by the British in the 1860s to map Tibet in secret. Foreigners were not allowed into Tibet then.
• They counted their steps on prayer beads. Each bead stood for a fixed number of paces, which gave the distance walked.
• They hid their instruments, for example inside prayer wheels.
• Nain Singh Rawat fixed the position of Lhasa, the capital of Tibet.

6. Geodetic datum: Everest spheroid vs WGS-84

• Geodetic datum: the model of the earth's shape that a map uses to give coordinates (latitude and longitude).
• The earth is not a perfect ball. It bulges at the equator and is flat at the poles.
• A spheroid (ellipsoid: a slightly squashed sphere) is chosen to stand in for this shape.
• Different spheroids give slightly different latitude and longitude for the same spot.

Datum	Used for	Coverage
Everest spheroid (1830)	Old Indian maps and SoI sheets	Fits the Indian region well
WGS-84 (World Geodetic System 1984)	GPS and SoI Open Series Maps	Fits the whole earth (global)

• Result: the same point can have slightly different coordinates on an old sheet and a new one. A GPS reading must be converted before it is plotted on an Everest-datum toposheet.

7. National Atlas and Thematic Mapping Organisation (NATMO)

• Thematic map: a map that shows one subject, such as rainfall, population, soils or crops.
• NATMO: India's agency for national atlases and thematic maps.

Feature	Fact
Founded	1956, as the National Atlas Organisation (NAO). Jawaharlal Nehru approved it [3]
Founder-Director	Prof. S.P. Chatterjee, a leading Indian geographer [3][5]
Renamed	1978, as NATMO, to give it a wider role in thematic mapping and geographical research [3]
Headquarters	Kolkata (West Bengal)
Parent body	Attached office of the DST [5]
First atlas	Bharat Rashtriya Atlas (Hindi), 1957: 26 multi-colour maps at 1:5 million. It was made in nine months [3][5]
Output	100+ atlases, 500+ thematic maps, ~200 monographs and 50+ cartographic services (DST, accessed 2026) [5]
Digital tools	Uses GIS, GPS and remote sensing. It holds the country's largest store of spatial and non-spatial data [3]
Geo-portal	Manchitran. It was launched within six months of the government freeing up geospatial data (2021). It gives free e-Atlases and PDF maps, with map services that follow OGC (Open Geospatial Consortium) standards and run 24×7 [5]

8. Old vs modern institutions at a glance

Body	Year	HQ	Main job
Survey of India	1767	Dehradun	Topographical maps, geodetic control, boundaries
NATMO	1956 (renamed 1978)	Kolkata	National Atlas, thematic maps

Prelims Hooks

• Survey of India was set up in 1767. It is the oldest scientific department of the Government of India. HQ: Dehradun. Ministry: DST. Head: Surveyor General.
• Map of Hindustan (1785) → James Rennell, who was made Surveyor General of Bengal in 1767.
• Great Trigonometrical Survey → started 1802, Madras, by William Lambton. The method was triangulation along the Great Arc.
• George Everest was Surveyor General from 1830 to 1843. Radhanath Sikdar found Peak XV to be the highest peak (~1852). It was named Mount Everest in 1865.
• Nain Singh Rawat (a Pundit) → fixed the position of Lhasa. The Pundits measured distance by counting paces on prayer beads.
• Everest spheroid (1830) = old Indian datum. WGS-84 = GPS and Open Series Maps. Trap: the two give slightly different coordinates for the same point.
• NATMO: Kolkata, set up 1956 as the National Atlas Organisation, renamed 1978, under DST. Founder: S.P. Chatterjee.
• First National Atlas, Bharat Rashtriya Atlas (1957, Hindi): 26 maps at 1:5 million.
• Match the HQ: SoI → Dehradun. NATMO → Kolkata. Both come under DST.
• SoI's three main toposheet scales: 1:250,000, 1:50,000, 1:25,000.

Mains Points

• Mapping was tied to colonial power.
• The East India Company surveyed land to collect revenue, move troops and fix borders.
• The GTS and the secret Pundit missions into Tibet show how science served empire.

• The same work left India with world-class geodetic control [2][4] (GS-I: history of the modern world and geography).

• Indian talent in science.

• Radhanath Sikdar's calculation of Peak XV and Nain Singh Rawat's fix of Lhasa show that Indians did key scientific work.

• Colonial naming hid their role: the peak was named after Everest, not after Sikdar.

• From paper to digital maps.

• SoI's Digital Centres (late 1980s) began this shift [2][4].
• NATMO's GIS work and its free Manchitran portal [5] carried it further.

• The National Geospatial Policy 2022 [2] made geospatial data easier to get for planning, disaster management and infrastructure (GS-III).

• Datum change matters in practice.

• The move from the Everest spheroid to WGS-84 makes Indian maps match GPS and global datasets.
• Old and new sheets must be converted carefully when they are used together. Otherwise land records and boundary work can go wrong.