GEOGRAPHIC INFORMATION SYSTEM
1 SPATIAL DATA
Spatial data (mapable data) of geo-referenced data is commonly characterized by the presence of two fundamental components.
(i) The physical dimension or class i.e., the phenomena being reported.
For example : Height of the forest canopy, demographic class, rock type, regetation type details of a city etc.
(ii) The spatial location of the phgenomena
For example : Specified with reference to common coordinate system (latitude and longitude etc).
2 2 NON SPATIAL / ATTRIBUTE / A SPATIAL OR TABULAR DATA
1. There are usually data tables that contain information about the spatial components of the GIS theme. These can be numeric and/or character data such as timber type, timber volume, road size, well depth etc. The attributes are related back to the spatial features by use of unique identifiers that are stored both with the attribute tables and the features in each spatial data layer. Attributes can be either qualitative (low, medium, high income) or quantitative (actual measurements). The database allows us to manipulate information in many ways : from simple listing of attributes, sorting features by some attributes, grouping by attributes, or selecting and singling out groups by attributes.