Data in GIS (Spatial and Non-Spatial Data)

One of the main element of GIS is data. The prime aspect in the construction if GIS is the acquisition of data. Data in GIS can be classified as spatial and non-spatial data.

Data in GIS

1. Spatial Data 

Any data which contains the information about the specific location on the earth surface is called Spatial Data. In simple terms, data which answer any question related to WHERE? is a spatial data. It is also termed as a geospatial data. The most important feature of spatial data is it can numerically represent any physical object in a geographical coordinate system. Nevertheless, Spatial data can exist in many formats and can also contain more than just a location specific information.

Spatial data formats

a) Vector data 

 Vector data are the graphical representation of the real world. Vector data depicts the real world by the means of discrete points, lines and polygons and it is stored as a collection of x,y coordinates. There are mainly 3 types of vector data:

i) Point

It is represented as a single pair of coordinates and the simplest vector data.

Fig: Point Data in GIS

ii) Line 

It is represented as a strings of coordinates which starts and ends with node.

Fig: Line Data in GIS

iii)  Polygon 

It is represented as a closed loop of coordinates.

Fig: Polygon Data in GIS

b) Raster Data

Raster data illustrates the real world by pixels or grid cells and it is also termed as cellular data. Each cell in a raster has a value which provides the information about the element in question. Raster usually refers to images. Some examples of raster are aerial photographs, satellite images. The quality of raster data depends on the resolution of raster.

Fig: Raster Data in GIS

2) Non-Spatial data 

 It is also called as attribute data. These data are alpha numeric and provides information about color, texture quality and quantity. Spatial data needs attribute data to provide additional meaning. For instance, an attribute data can be area of a building, color of building, number of people living in that building and many more.

Fig: Non-Spatial/Attribute Data in GIS