Open Series and Defence Series Maps today

Detail

Why India has two series of maps

• Survey of India (SoI) is India's National Mapping Agency. It is under the Department of Science and Technology (DST). It makes, updates and gives out the topographic maps of the whole country [2].
• Topographic map: a large-scale map that shows the land's relief (contours, spot heights) along with rivers, roads, settlements and vegetation.
• The problem:
• Planners need detailed maps for roads, dams, cities and relief work after disasters.

• The same detail (exact heights, military sites) can harm national security if anyone can get it.

• The answer, National Map Policy 2005:

• It split SoI topographic maps into two series. The aim was to keep security safe and still open up map data for development [2].

• Both series come from one master database, the National Topographical Database (NTDB) [2].

• NTDB has five data sets [2]:

• National Spatial Reference Frame
• National Digital Elevation Model
• National Topographical Template
• Administrative Boundaries
• Toponymy (place names)

Key terms

• Datum: a reference model of the Earth's shape. A map's latitudes, longitudes and heights are measured against it.
• Everest datum: India's old datum. It is based on the Everest spheroid and fits the Indian subcontinent well, but not the rest of the world.

• WGS-84 (World Geodetic System 1984): a global datum. GPS uses it, so maps on WGS-84 match satellite and GPS data directly.

• Projection: a method of drawing the curved Earth on a flat sheet (see map-projections).

• Polyconic: the older projection used on SoI sheets.

• UTM (Universal Transverse Mercator): a global grid. It splits the world into 60 zones, each 6° of longitude wide.

• Vulnerable Areas and Vulnerable Points (VAs/VPs): sensitive civil and military sites, such as defence bases and key installations. They must not be shown on public maps [2].

Defence Series Maps (DSMs)

• Definition: topographic maps with full content, heights and contours and no loss of accuracy, on various scales [2].
• Datum and projection: Everest or WGS-84 datum, on Polyconic or UTM projection [2]. This means they keep the older Everest/Polyconic system alongside the newer one.
• Users: mainly defence and national security needs [2]. They are not sold to the public.
• Control:
• The whole series, paper or digital, is classified (kept secret) as needed [2].
• The Ministry of Defence (MoD) makes the rules for their use [2].

Open Series Maps (OSMs)

• Definition: maps made only by SoI, mainly to support development work across the country [2].
• Datum and projection: WGS-84 datum on UTM projection only [2].
• Sheet numbers: OSMs have different sheet numbers from DSMs [2].
• Security clearance:
• Each OSM (paper or digital) needs a one-time clearance from MoD. After that it becomes "Unrestricted" [2].
• SoI makes sure no VAs/VPs appear on OSMs [2].

• Contours and heights are left out in restricted zones, as MoD instructs [2].

• What an OSM still shows [2]:

• lat/long, sheet number, year of survey, magnetic variation and the Representative Fraction (RF)
• administrative boundaries from the international boundary down to the village, including boundary pillars and village trijunctions
• all roads, tracks, passes, railways and tunnels
• all streams, canals, earthwork dams, wells, springs and tanks
• settlements, forts, religious places and police stations
• transmission lines
• relief: contours, sand features, ice forms, spot heights and benchmarks

• vegetation, and reserved or protected forests

• How users get them:

• OSMs at scales larger than 1:1 million can be sold, or given under an agreement for a stated end use [2].
• Each deal is recorded in a Map Transaction Registry [2].
• At first, buyers signed an undertaking (a written promise about how they will use the map).

• Today, OSMs can be downloaded from SoI's online maps portal.

• Value addition:

• Users may add their own data to OSMs and publish them on paper or on the web, with or without a GIS database [2].

• A map that shows the international boundary needs SoI certification [2].

• City Maps: SoI also makes large-scale City Maps on WGS-84. These are in the public domain, and their content is decided with MoD [2].

DSM and OSM compared

Feature	Defence Series Maps	Open Series Maps
Purpose	Defence, national security	Civil and development use
Datum / projection	Everest or WGS-84; Polyconic or UTM	WGS-84; UTM only
Content	Full content, heights and contours, full accuracy	VAs/VPs removed; no contours or heights in restricted zones
Status	Classified; MoD rules	"Unrestricted" after one-time MoD clearance
Access	Armed forces only	Public (sale, agreement, now online download)
Sheet numbers	Original series	Separate numbering

Geospatial Guidelines 2021: opening up further

• Issued by: DST, on 15 February 2021. The full name is "Guidelines for acquiring and producing Geospatial Data and Geospatial Data Services including Maps" [3][4].
• Geospatial data: any data tied to a place on Earth, such as maps, satellite images, survey points and elevation.
• What changed:
• No prior approval, security clearance or licence is needed to collect, make, store, publish or digitise geospatial data and maps within India [3][4].
• Indian entities, government or private, may make geospatial data of any accuracy. This includes underwater data within India's territorial waters [3][4].

• There is no negative list of prohibited areas [3].

• What stays restricted:

• Only a negative list of sensitive attributes stays regulated. DST notifies this list [3][4].

• Negative list: a short list of sensitive features (attributes) that cannot be marked on any map or linked to any place on a map [3].

• Why it was done:

• Indian firms can now compete in global mapping.
• Datasets made with public money reach more users [3].

National Geospatial Policy (NGP) 2022 (detail in remote-sensing-gis)

• Aim: a citizen-centred policy. Geospatial data made with public funds should be openly available [5][6].
• Geospatial Knowledge Infrastructure (GKI): a national system of geospatial data, services and platforms, built on an Integrated Data and Information Framework [5][6].
• Targets by 2030 [5][6]:
• High-resolution topographic survey and mapping:
  • 5–10 cm resolution for urban and rural areas
  • 50–100 cm for forests and wastelands

• High-accuracy national DEM:

  • 25 cm accuracy for the plains
  • 1–3 m for hilly and mountainous areas

• DEM (Digital Elevation Model): a digital grid of ground heights. It is the computer form of the contours and spot heights on a topographic sheet.

Field uses of OSMs and new map data

• Watershed and irrigation planning:
• Contours show where water flows and where ridges divide catchments.

• Planners use this to place check dams, tanks and canals.

• Road and rail alignment:

• Contour spacing shows the slope.

• Engineers use it to pick gentle gradients, plan cuttings and tunnels, and avoid steep or unstable ground.

• Disaster risk mapping in the Himalaya:

• Slope, relief and drainage from the sheets help mark areas at risk of landslides, floods and glacial lake outbursts.

• Village base maps, SVAMITVA:

• SVAMITVA stands for Survey of Villages and Mapping with Improvised Technology in Village Areas. It is a Central Sector Scheme of the Ministry of Panchayati Raj, launched on 24 April 2020 (National Panchayati Raj Day) [7][8].
• Goal: give a "Record of Rights" (legal property cards) to house owners in the abadi areas of villages (the inhabited part of a village) [7].
• How it works:
  • SoI flies survey-grade drones over the village.
  • CORS (Continuously Operating Reference Stations: fixed GNSS stations that correct positions all the time) make the positions precise.
  • The result is large-scale maps with accuracy up to 5 cm [7].
• Progress (Parliament reply, 2025): drone survey done in 3.30 lakh villages. 3.24 crore property cards were prepared for 1.97 lakh villages, and about 2.72 crore had been given out [7].
• Benefits: owners can use their homes as collateral for bank loans, property disputes fall, and Gram Panchayats can plan better [7][8].

Prelims Hooks

• The National Map Policy 2005 created two series: Defence Series Maps (DSMs) and Open Series Maps (OSMs) [2].
• OSMs use WGS-84 datum + UTM projection only. DSMs may be on Everest/WGS-84 and Polyconic/UTM [2].
• OSMs become "Unrestricted" after a one-time clearance by the Ministry of Defence. DSM rules are also set by MoD, not by SoI [2].
• Trap: OSMs do show contours and spot heights. Only in restricted zones are contours and heights removed [2].
• A map showing the international boundary needs SoI certification [2].
• Geospatial Guidelines, 15 Feb 2021 (DST): no negative list of areas, only a negative list of sensitive attributes. No prior approval is needed for Indian entities [3][4].
• NGP 2022 targets for 2030: DEM accuracy of 25 cm in plains and 1–3 m in hills. Topographic survey at 5–10 cm for urban and rural areas [5][6].
• SVAMITVA: Ministry of Panchayati Raj, launched 24 April 2020. Drone mapping by Survey of India with CORS, accuracy up to 5 cm [7][8].
• The National Digital Elevation Model is one of the five data sets of SoI's NTDB [2].

Mains Points

• Security vs development (GS-I/III):
• The 2005 two-series policy separates secret military detail (DSMs) from cleaned civil maps (OSMs).
• This lets planners use the same national database without exposing VAs/VPs.

• The cost: contours and heights are missing in restricted zones. These are often the border Himalayan districts where disaster planning needs them most.

• From control to openness (GS-III, infrastructure):

• The 2021 Guidelines replaced the old "permission first" system with a short negative list of attributes.
• NGP 2022 adds open access to publicly funded data and a national DEM by 2030.

• Together they cut delays for roads, railways, irrigation and smart-city projects, and help Indian mapping firms grow.

• Disaster management (GS-III):

• High-resolution DEMs (1–3 m in hills) let agencies model landslide, flash-flood and GLOF risk in the Himalaya much better than older contour sheets.

• Examples: slope-failure zones along hill roads, and flood paths below glacial lakes.

• Rural governance (GS-II/III):

• SVAMITVA turns cm-level drone maps into legal property cards (3.24 crore prepared, 2025).
• Rural homes become bankable assets (they can back a loan), and these maps form the village base for Gram Panchayat Development Plans [7].