Vector Data

Vector is a data structure, used to store spatial data. Vector data is comprised of lines or arcs, defined by beginning and end points, which meet at nodes.

v  The locations of these nodes and the topological structure are usually stored explicitly.

v  Features are defined by their boundaries only and curved lines are represented as a series of connecting arcs.

v  Vector storage involves the storage of explicit topology, which raises overheads, however, it only stores those points which define a feature and all space outside these features is 'non-existent'.

Co-ordinate

Pairs of numbers expressing horizontal distances along orthogonal axes, triplets of numbers measuring horizontal and vertical distances, or n-numbers along n-axes expressing a precise location in n-dimensional space. Coordinates generally represent locations on the earth's surface relative to other locations.

Point

A zero-dimensional abstraction of an object represented by a single X, Y coordinate. A point normally represents a geographic feature too small to be displayed as a line or area; for example, the location of a building located on a small-scale map, or the location of a service cover on a medium-scale map.

 Line

A set of ordered coordinates
that represent the shape of geographic features too narrow to be displayed as an area at the given scale (contours, street centrelines, or streams), or linear features with no area (county boundary lines). A line is synonymous with an arc.

Arc

An ARC/INFO term that is used synonymously with line.

Polygon

A feature used to represent areas. A polygon is defined by the lines that make up its boundary and a point inside its boundary for identification. Polygons have attributes that describe the geographic feature they represent.