How geotagging of buildings will work during Census, how it will help

GIS is a computer system that captures, checks, and displays data on specific positions on the surface of the Earth.

Latitudes and longitudes are imaginary lines that are used to determine the location of a place on the globe. Latitudes (or ‘parallels’) are horizontal lines that indicate the north-south distance of a place from the equator; longitudes (or ‘meridians’) are vertical north-south lines that determine the east-west distance of a place from the prime meridian, which passes through Greenwich, UK.

Together, lines of latitude and longitude imagine a grid on the surface of the Earth. Any location can be described by the point where a specific latitude and longitude intersect.

Geotagging provides a building with a precise and unique locational identity that can be pinpointed with accuracy.

And how many ‘buildings’ are there in the country?

Census 2011 defined a ‘Census House’ as “a building or part of a building used or recognized as a separate unit because of having a separate main entrance from the road or common courtyard or staircase etc”.

A Census House may be occupied or vacant; it may be used for residential or non-residential purposes, or for both.

The last Census (2011) recorded 330.84 million houses in India, of which 306.16 million were occupied and 24.67 million were vacant. 220.70 million houses were in rural areas, and 110.14 million were in urban areas.

How will the geotagging exercise take place?

Geotagging will be done during the Houselisting Operations (HLO), the first phase of the Census, which is scheduled for April-September 2026. (The second phase is of Population Enumeration (PE), during which demographic, socioeconomic, and cultural data of individuals will be collected.)

It is learnt that enumerators will visit buildings in the Houselisting Blocks (HLBs) assigned to them, and geotag each building using Digital Layout Mapping (DLM). Enumerators can switch on the current location on their smartphones and list the building using the mobile application.

An HLB is “a well-defined area in a village or in a ward of the town which can be clearly demarcated on the ground and for which a notional map is drawn for the purpose of the Census Operations”.

Data will be collected on the number of Census Houses and Households residing in each building. Buildings will be classified in categories such as ‘residential’, ‘non-residential’, ‘partly residential’, and ‘landmark’.

Census 2011 defined a ‘household’ as a group of persons who normally live together and take their meals from a common kitchen, unless the exigencies of work prevent any of them from doing so.

How will the geotagging of buildings during the Census help?

According to sources, geotagging will help to accurately estimate the number of Census houses and households requiring enumeration, thus improving workload management across field functionaries.

In earlier Censuses, notional sketches were drawn by hand as part of the houselisting exercise.

However, the government has been using geotags on a smaller scale – for example, assets such as houses constructed under the Pradhan Mantri Awaas Yojana-Gramin and PMAY-Urban are geotagged.