Spatial Data Types and Models

Spatial data is the data collected through with physical real life locations like towns, cities, islands etc. Spatial data are basically of three different types and are wisely used in commercial sectors :

1. Map data : Map data includes different types of spatial features of objects in map, e.g – an object’s shape and location of object within map. The three basic types of features are points, lines, and polygons (or areas).
   • Points – Points are used to represent spatial characteristics of objects whose locations correspond to single 2-D coordinates (x, y, or longitude/latitude) in the scale of particular application. For examples : Buildings, cellular towers, or stationary vehicles. Moving vehicles and other moving objects can be represented by sequence of point locations that change over time.
   • Lines – Lines represent objects having length, such as roads or rivers, whose spatial characteristics can be approximated by sequence of connected lines.
   • Polygons – Polygons are used to represent characteristics of objects that have boundary, like states, lakes, or countries.
2. Attribute data : It is the descriptive data that Geographic Information Systems associate with features in the map. For example, in map representing countries within an Indian state (ex – Odisha or Mumbai). Attributes- Population, largest city/town, area in square miles, and so on.
3. Image data : It includes camera created data like satellite images and aerial photographs. Objects of interest, such as buildings and roads, can be identified and overlaid on these images. Aerial and satellite images are typical examples of raster data.

Models of Spatial Information : It is divided into two categories :

• Field : These models are used to model spatial data that is continuous in nature, e.g. terrain elevation, air quality index, temperature data, and soil variation characteristics.
• Object : These models have been used for applications such as transportation networks, land parcels, buildings, and other objects that possess both spatial and non-spatial attributes. A spatial application is modeled using either field or an object based model, which depends on the requirements and the traditional choice of model for the application. Example – High traffic analysing system, etc.