What is Vector data?
A. The Association for Geographic Information’s definition of Vector Data is: – An abstraction of the real world where positional data is represented in the form of co-ordinates. In vector data, the basic units of spatial information are points, lines and polygons. Each of these units is composed simply as a series of one or more co-ordinate points, for example, a line is a collection of related points, and a polygon is a collection of related lines. The OSNI Large Scale database consists of 1:1250 and 1:2500 scale vector mapping and the Pointer address database. It forms the basis on which spatial information in Northern Ireland is held, or is related to, either directly through a coordinated position on the Irish Grid, or indirectly through an address or administration area. All features are recorded as cartographic elements – lines, symbols, text etc. – with related attributes, within a hierarchical framework to categorize them by type of feature (building, wall, road edge, administ
