Geospatial technology

The first principle

Every planning decision is a question about place: where to build, what is changing and who is affected. Geospatial technology answers such questions by joining three abilities: seeing the earth from above (remote sensing), knowing exactly where any point is (satellite navigation), and combining many maps of the same place to find patterns (Geographic Information System). Drones and Artificial Intelligence (AI) add detail and speed, so that a task like mapping every house in a village, once a survey of years, now takes days.

The core

Remote sensing (RS)

Remote sensing means gathering information about the earth without touching it, by recording the energy that surfaces reflect or emit. Each material, such as healthy crops, water, concrete or bare soil, has its own spectral signature, so an image can tell them apart.

• Passive sensors record reflected sunlight or emitted heat, as in the Resourcesat and Cartosat series of the Indian Space Research Organisation (ISRO); they cannot see through cloud or at night.
• Active sensors send their own microwave pulses and record the echo, so Synthetic Aperture Radar (SAR) satellites such as RISAT and EOS 04 see through monsoon cloud, day and night, which is vital for floods and crops in kharif. NISAR, a joint NASA and ISRO radar satellite launched in July 2025, maps the whole earth's land and ice every 12 days.
• Resolution comes in four kinds: spatial (the smallest object seen), spectral (number of wavebands), temporal (how often a place is revisited) and radiometric (how finely brightness is measured). A sensor trades one against another, which is why missions are designed for specific uses.

Geographic Information System (GIS)

A GIS stores data as layers tied to the same coordinates, such as land use, roads, soils, slope, population and land records. Overlay analysis combines layers to answer questions no single map can, for example "flat land within 2 km of a road, outside forest and flood zones" for a new school or industrial park. GIS also handles buffers, network routing and change over time.

Global Navigation Satellite System (GNSS) and why India needs its own

A navigation receiver works out its position by timing signals from several satellites. Each satellite broadcasts its position and the exact time from an atomic clock; since radio waves travel at the speed of light, the delay gives the distance, and distances to four satellites fix latitude, longitude, height and the receiver's clock error. An error of one millionth of a second in time means an error of 300 m in distance, which is why atomic clocks are the heart of the system.

The United States Global Positioning System (GPS) is controlled by the United States military. During the Kargil conflict in 1999, India sought GPS data for the region and was denied it, which showed that a country relying on a foreign system could lose it when it needs it most. India therefore built the Indian Regional Navigation Satellite System (IRNSS), named NavIC (Navigation with Indian Constellation).

• Constellation design. NavIC was designed with seven satellites at about 36,000 km: three in geostationary orbit over the equator at 32.5°E, 83°E and 129.5°E, and four in geosynchronous orbits inclined at about 29°, crossing the equator at 55°E and 111.75°E and tracing a figure of eight. Because all of them stay over the Indian region, a receiver in India always sees them, so a regional system needs far fewer satellites than the roughly 24 to 31 of global systems.
• Coverage and accuracy. It covers India and about 1,500 km around it, with position accuracy better than 20 m in the primary area, and better in practice.
• Services. The Standard Positioning Service is open to civilian users, while the encrypted Restricted Service is for the armed forces and authorised users.
• Uses. It supports vehicle tracking (mandatory for public transport and commercial vehicles under the vehicle tracking rules), alerts to fishermen at sea about cyclones and maritime boundaries, disaster warnings, surveying, and precise timing for power grids, telecom networks and bank transactions.

Dimensions

• Strategic. An independent system means navigation for missiles, ships and troops cannot be switched off by another country.
• Economic. Accurate location underpins logistics, ride hailing, precision farming and insurance, and the National Geospatial Policy expects geospatial services to grow into a large industry.
• Governance. Maps make land, assets and services visible, which reduces disputes and leakages.
• Environmental. Satellite time series track forest cover, glacier retreat, wetland loss and coastal erosion, as the India State of Forest Report does every two years.
• Privacy and security. High resolution images and location data raise questions of surveillance and sensitive sites.

In practice

Using AI and drones with GIS and RS in locational and areal planning

• Property and land records. SVAMITVA (Ministry of Panchayati Raj, 2020) uses drones to map inhabited rural land and issue property cards, which lets owners take loans and reduces disputes; drone surveys covered over 3 lakh villages by early 2025. The Digital India Land Records Modernisation Programme links such maps to land records.
• Urban master plans. Drone and satellite maps, analysed in GIS, give the base for master plans under the Atal Mission for Rejuvenation and Urban Transformation (AMRUT) sub scheme for GIS based master plans, while AI extracts building footprints and road networks quickly and spots unauthorised construction by comparing images over time.
• Agriculture. Under the Pradhan Mantri Fasal Bima Yojana, satellite data and AI estimate crop area and yield, so claims are settled faster and with less dispute, and drones spray inputs and assess damage.
• Disasters. Radar satellites map flood extent through cloud, drones survey landslides and damaged houses, and GIS hazard maps guide where not to build.
• Infrastructure. PM GatiShakti National Master Plan (2021) brings hundreds of data layers of many ministries onto one GIS platform, built with the Bhaskaracharya National Institute for Space Applications and Geo informatics (BISAG N), so a road or pipeline can be aligned to avoid forests and settlements.
• Digital twins. A digital twin is a three dimensional, constantly updated model of a city or river basin, built from these data, on which planners can test a flood or a new metro line before acting.

Policy

• Guidelines for geospatial data (Department of Science and Technology, February 2021) removed the need for prior approval to collect and publish most maps, opening the sector to Indian companies.
• Drone Rules, 2021 (Ministry of Civil Aviation) cut forms and fees, created green, yellow and red airspace zones and the Digital Sky platform, followed by a production linked incentive scheme.
• National Geospatial Policy, 2022 aims for high resolution topographic mapping and a national digital twin by 2035.

Issues and way forward

• NavIC's clock problem. The imported rubidium atomic clocks on IRNSS 1A failed, and IRNSS 1I replaced it in 2018; other first generation satellites have also lost clocks, so fewer than the designed number have been fully usable. ISRO's second generation NVS series carries an Indian made atomic clock and a new L1 band signal that phones can receive easily; NVS 01 launched in May 2023, but NVS 02 (January 2025) could not reach its planned orbit after a valve on its engine failed. Launching the remaining NVS satellites on schedule is the main task.
• Low adoption. Few phones and chips used NavIC until recently; requiring it in more devices and public systems, as the government has pushed, would build a market.
• Data silos and quality. Departments hold maps in different formats; the National Geospatial Policy calls for common standards and open data.
• Skills and privacy. Local bodies lack GIS staff, and India needs clear rules on location data under the Digital Personal Data Protection Act, 2023.
• AI errors. Automated extraction can misclassify informal settlements or crops, so ground checking must remain part of any decision that affects rights.

Common confusions

• GPS and GNSS. GPS is the American system; GNSS is the general term for all systems, including Russia's GLONASS, Europe's Galileo, China's BeiDou and India's NavIC.
• Geostationary and geosynchronous. Both orbit once a day; a geostationary satellite is over the equator and appears fixed, while a geosynchronous one is inclined and traces a figure of eight.
• Remote sensing and GIS. Remote sensing collects data; GIS stores, combines and analyses it.
• Spatial and spectral resolution. Spatial resolution is how small an object can be seen; spectral resolution is how many colours (wavebands) are recorded.

For the exam

• Keyword bank: remote sensing, spectral signature, synthetic aperture radar, spatial resolution, GIS overlay, GNSS, NavIC, geosynchronous orbit, atomic clock, restricted service, SVAMITVA, digital twin, PM GatiShakti, National Geospatial Policy.
• Previous year questions: Practise the previous year questions on this topic →
• Use in an answer:
  • Introduction (data): Under SVAMITVA, drones had surveyed over 3 lakh villages by early 2025, turning unmapped homes into property cards that owners can use as collateral.
  • Introduction (event): During Kargil in 1999 India was denied GPS data for the region, a lesson that led directly to NavIC.
  • Conclusion: Remote sensing tells us what is where, GIS tells us what it means, and AI and drones let us do both at the scale of a nation, so geospatial capacity is now basic infrastructure.
  • Conclusion: An independent navigation system is as much a part of sovereignty as a currency or an army, so completing the NVS series is a strategic priority.