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
- 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
- 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
Conclusion
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 Singh is a PhD from the Center for the Study of Regional Development, Jawaharlal Nehru University, New Delhi. She has six years of experience as an Assistant Professor of Geography at Kamala Nehru College, University of Delhi.