Geospatial data is primarily of two types in GIS i.e. spatial data and non-spatial data. Geographical Information System (GIS) is a computer-based programming system which integrates hardware, software, data and user interface for capturing, analyzing and presenting all forms of geographically referenced information over the surface of the earth.
- It allows users to analyze and visualize data in dynamic ways that reveal the relationship between patterns and trends of phenomena.
- The database information is tied to spatial data which aids in areal association and spatial differentiation. Based on this, database is primarily of two types- spatial and non-spatial database.
- Spatial data is the geographical representation of features.
- It includes location, shape, size, orientation and association of the geographic field and object. Such data is multidimensional and autocorrelated in nature i.e. triangular, rectangular, quadrilateral etc. (See Fig.1)
- For example, a parcel of square land in which its center specifies its location, its shape is square, angle is its diagonals and the x-axis specifies its orientation.
- Hence, spatial data is the visualization of geographical phenomena over a spatial plane. It consists of vector and raster data based on its layer of representation.
- Non-spatial data is also known as attribute data or characteristic data.
- This information is in form of numbers and words e.g. population density, literacy rate, pollution level etc.
- It consists of the spatial features which are independent of all geometric considerations and from locational information.
- Such data do not mention the latitudinal and longitudinal expanse of the object but only mention the name of location. (See Table 1)
- For example, the non-spatial data of a city comprise of the name of the city, its population, settlement types, administration set-up, education facilities, means of transport and communication etc.
- It is important to note that all the above-mentioned data of the city are not dependent on their location identities.
- Hence, non-spatial data is independent from location information.
- They are one dimensional as they are represented in GIS in a tabular format with a unique identifier for each object. (See Table 1)
Table 1 Shape_ID Shape_Name Illegal Building Present Source of Pollution 1 RiverYamuna.shp 10 Sewerage 2 Forest.shp 5 Garbage Dumping 3 GovtLand.shp 4 Garbage Dumping
Hence, the primary difference between spatial and non-spatial data is that the spatial data contains the locational expanse in terms of latitude and longitude (UTM) whereas the non-spatial does not contain this information.
Dr. Nisha is an Assistant Professor of Geography at Kamala Nehru College, University of Delhi.