Spatial information technology and GIS: concepts and components

Detail

1. Why a new technology was needed

• Computers first gave geographers two useful tools:
• Database management system (DBMS): software that organises, stores and processes data kept in tables (rows and columns). Example: a register of village names and their populations.

• Computer-assisted cartography: drawing maps with a computer instead of by hand.

• Their limit: neither tool can answer the questions a planner actually asks:

• What is where?
• Why is it there?

• What if it moves or changes?

• A DBMS knows "what" but not "where". Computer cartography knows "where" but cannot analyse "why" or "what if". So a tool was needed that joins location with analysis.

2. Spatial information technology

• Spatial information technology: the use of technology to collect, store, retrieve, display, manipulate, manage and analyse information that is tied to locations on the earth.
• It brings five tools together:

Tool	What it does in the system
Remote sensing	Collects images of the earth from aircraft or satellites (from aerial photography to Landsat in 1972 and IRS-1A in 1988)
GPS / GNSS	Gives the exact position (latitude, longitude, height) of a point on the ground
GIS	Stores, combines and analyses data linked to places
Digital cartography	Makes maps on the computer from the data
DBMS	Manages the tables of descriptive data

3. Geographic information system (GIS)

• Geographic information system (GIS): a system for capturing, storing, checking, integrating (combining), manipulating, analysing and displaying data that are spatially referenced to the earth. "Spatially referenced" means each piece of data is linked to a real place on the earth.
• GIS became possible from the mid-1970s, when computers grew powerful enough to handle maps and tables together.
• GIS borrows from several fields:
• cartography (map-making)
• statistics
• computer science
• remote sensing

• many applied sciences, such as planning, agriculture and hydrology.

• Class 11 Geography as a Discipline notes that GIS and GPS have widened the scope of geography. Geography moved from describing places to measuring them, modelling them and planning for them.

4. Two forms of geographical information

Form	Meaning	Example (NCERT Box 4.1)
Spatial data	Data tied to a location and registered to a coordinate system (a fixed grid of latitude–longitude or map coordinates)	State-wise literacy rates are spatial, because each state has a location on the map
Non-spatial / attribute data	Descriptive data about a feature, without any location of their own	A cycle shop's stock register (models, prices, quantities) is non-spatial

• Key idea: a GIS links the two. The polygon of a state (spatial) is joined to its literacy figure (attribute). This makes analysis possible.
• Trap: the same table becomes spatial once each row is tied to a place. A literacy table is spatial because "Kerala" or "Bihar" can be found on a map.

5. Point, line and area features (NCERT Fig. 4.1)

Every real-world object is stored in a GIS as one of three simple shapes:

Feature type	Nature	Examples
Point	Positional: one location, no length or area	Wells, towns (at small scale), bus stops, tube wells
Line	Linear: has length but no width at map scale	Roads, rivers, railway lines, canals
Area / polygon	Areal: a closed boundary that covers space	Lakes, districts, forests, land-use parcels

• The choice depends on scale. A city is a point on a map of India but an area on a district map.

6. Sources of spatial data

There are three ways to get spatial data:

1. Buy digital data from suppliers. In India this includes government sources such as Survey of India and the NRSC (National Remote Sensing Centre) geoportal Bhuvan.
2. Digitise existing paper maps, i.e. convert them into computer form by tracing or scanning them.
3. Carry out your own surveys, using ground survey, GPS or remote sensing. - The choice depends on the application, the budget and the data structure needed. - Bhuvan (Sanskrit for "Earth") is ISRO's geoportal at bhuvan.nrsc.gov.in. It lets users view remote sensing data and download satellite data free of cost. Government departments can also host their own applications on it [4]. - It runs about 150 web services that departments use for geospatial governance (governing with the help of maps and location data) [5]. - Its modes include Standard, Thematic (natural-resource layers made by NRSC with State Remote Sensing Applications Centres), Data Hub & Analytics, and Disaster Services (near-real-time alerts) [5].

7. Advantages of GIS over manual (paper) maps

• The problem with a paper map:
• It fixes one presentation and one theme, such as only soils or only roads.

• To change the theme, scale or colours, it must be redrawn.

• How GIS solves it: it stores the data separately from the display. The same data can therefore be shown in many ways. Users can:

• Query features: click a feature and get its attributes (e.g. click a district and see its population).
• Draw maps from attribute queries: e.g. "show all districts with literacy below 60%".
• Run overlay analysis: stack layers on top of each other (soil + slope + rainfall) to find land suitable for a crop.
• Run buffering: draw a zone of fixed width around a feature (e.g. 500 m on both sides of a river or highway) to see what falls inside it.
• Link attributes through a shared location code: join two different tables (e.g. Census data and health data) using a common code, such as a district code.

8. Components of GIS (NCERT Fig. 4.2)

Component	What it includes
Hardware	Computer, storage, digitiser or scanner, printer or plotter, GPS units
Software	Three modules: (i) data entry and editing, (ii) analysis (query, overlay, buffer), (iii) display and output (maps, tables, reports)
Data	Spatial and tabular (attribute) data. Data are the backbone of GIS, because without good data no analysis is possible
People	Users at every level, from engineers who build the system to planners and decision-makers who use its results
Procedures	Set methods for collecting, checking, analysing and presenting data, so that results are reliable

9. India's policy framework for geospatial data

• 2021 guidelines: the Government announced liberalised guidelines for acquiring and producing geospatial data and services, including maps [6].
• National Geospatial Policy (NGP) 2022:
• Notified on 28 December 2022. Its long-term vision runs to 2035. It aims to make India a global leader in the geospatial sector [3].
• Removed the old controls: prior approval, security clearance and licences for geospatial data and maps within India were dropped. The old clearance system was replaced by self-certification (users declare for themselves that they follow the rules) [2].
• Opened up public data: geospatial datasets made with public funds are to be openly accessible [3]. Individuals, companies and government agencies can process this data and build applications and solutions on it [2].
• Governance: the Geospatial Data Promotion and Development Committee (GDPDC) oversees the policy. The Survey of India plays a key role in carrying it out [7].
• Targets by 2030 [3]:
  • high-resolution topographic surveys at 5–10 cm accuracy for urban and rural areas, and 50–100 cm for forests and wastelands
  • a high-accuracy Digital Elevation Model (DEM: a digital map of ground height) at 25 cm for plains and 1–3 m for hilly and mountainous areas.
• Targets by 2035 [3]:
  • high-resolution bathymetric data (maps of underwater depth) for inland waters and the deep sea, to support the Blue Economy
  • mapping of sub-surface infrastructure (pipes and cables under the ground) in major cities
  • a National Digital Twin of major cities: a live digital copy of a city, used for planning.
• Implementation: Operation Dronagiri was launched together with the GDI (Geospatial Data Integration platform) (2024) as a milestone under the NGP [7].

Prelims Hooks

• GIS became possible from the mid-1970s. It draws on cartography, statistics, computer science and remote sensing.
• Spatial information technology = remote sensing + GPS + GIS + digital cartography + DBMS.
• NCERT Box 4.1: a cycle shop's stock register is non-spatial. State-wise literacy is spatial.
• Feature matches: wells or towns → point; roads or rivers → line; lakes or districts → polygon (area).
• Buffering = a zone of fixed distance around a feature. Overlay = stacking thematic layers. Both are GIS functions that paper maps cannot perform.
• The five components of GIS are hardware, software, data, people and procedures. Data are called the backbone.
• The three GIS software modules are data entry and editing, analysis, and display and output.
• Bhuvan is the geoportal of ISRO, developed and run by NRSC (Hyderabad). Its satellite data can be downloaded free [4].
• National Geospatial Policy was notified on 28 Dec 2022, with a vision to 2035. It replaced security clearance with self-certification [2][3].
• NGP target for 2030: a DEM at 25 cm accuracy for plains and 1–3 m for hills [3].

Mains Points

• GIS as a planning tool (GS-I/GS-III): GIS can query, overlay and buffer data, and keeps data separate from the display. It turns static maps into tools for decisions, such as:
• finding suitable sites for a facility (overlay)
• marking flood or industrial risk zones (buffering)

• joining Census and health data through district codes. This speeds up "what if" analysis in urban planning and disaster management.

• Data are the backbone, and policy now frees them: the 2021 guidelines and NGP 2022 removed licensing and clearances and opened up publicly funded data [2][3][6]. Together with free platforms like Bhuvan (about 150 web services) [5], this lowers costs for start-ups, states and researchers.

• Infrastructure targets show the next steps: cm-level topographic surveys and DEMs by 2030, and bathymetry, underground utility mapping and National Digital Twins by 2035 [3]. These support the Blue Economy, smart cities, flood modelling and the land-records work in projects such as Operation Dronagiri [7].
• Remaining challenges: the people and procedures components are still weak. There is a shortage of trained GIS staff, data standards differ between agencies, and digitised maps vary in quality. Adoption therefore lags behind what the data and policy now allow.