SPATIAL DATA TYPES
In a GIS, the Locational information is provided in maps by using Points, Lines and Polygons. These geometric descriptions are
the basic data elements of a map.
They are represented as a single ‘Dot ‘on the map.
o Points are used to indicate discrete locations.
o They have no length or area at the given scale.
o They usually have a single X, Y coordinate.
o Used to represent a feature that is too small to be displayed as a line or area.
(An example of Points)
2. Arcs / Lines:
Arcs are ordered sets of Points that have the look of a straight line or a curved arc depending upon the feature it describes.
o They have a length but no width.
o They are accompanied by a set of coordinates.
o They are used to represent a geographical feature that is too narrow to have area, such as a stream or a road.
(An example of Lines)
They are closed features whose boundary encloses a homogenous area.
o They have an area that is given by the arcs/lines that make the boundary.
o They are used to represent features that have area (e.g. lakes, large cities and islands)
(An example of Polygons)