Topographical Maps and Grid Systems

Vocabulary terms regarding the definition of topographical maps, the role of the Survey of India, and the components of the arbitrary grid system.

Topographical maps (or topo sheets)

Large-scale maps, prepared by the Survey of India based on actual field surveys, depicting landforms, drainage, land use, settlement patterns, and other features of a very small area.

Survey of India

The organization responsible for preparing large-scale topographical maps based on actual field surveys.

Grid

A network of latitudes and longitudes used to locate places on a map.

Arbitrary grid system

A network of vertical and horizontal lines drawn in red on a topo sheet, used to solve the difficulty of calculating exact latitude and longitude.

Eastings

The vertical red lines used in an arbitrary grid system on a topographical map.

Northings

The horizontal red lines used in an arbitrary grid system on a topographical map.

Grid square

A square formed by the network of vertical and horizontal lines in an arbitrary grid system.

South-west corner

The specific reference corner of a grid square as illustrated in the Fig. $1.1$ arbitrary grid system.

Conventional signs and symbols

Standardized representations on a topo sheet used to indicate features like aerodromes, boundaries, vegetation types, and road classifications.