Definition of GIS
The full form of GIS is Geographical Information System. GIS can be a defined as a computer based database management system which provides users various tools and functions for capturing, storing, analyzing, retrieving, and displaying spatial data.The processed geographic data is refered to as geographic information.
Role of GIS
GIS is widely used in many fields related to urban planning, water resources management, environmental engineering, transportation and traffic planning, off-shore engineering, telecom, surveying, military, etc.
Numerous open source, and proprietary GIS software are available, which provides a variety of tool boxes for users in the aforementioned and other fields for handling different tasks that involve spatial data. Some of the popular examples for the tasks involving spatial data include,preparation of spatial maps, spatial anlaysis of disease spread, etc.
Key terms in GIS
In order to effectively use the GIS, it is important to understand different terminology that is associated with GIS. Some of the widely used terms and their definitions are given below.
Spatial data
The data pertaining to any location on the earth surface can be termed as spatial data. Spatial data can comprise of data from several point locations spanning across an entire region, or it can be data pertaining to one or several regions as well. Some of the examples for spatial data include population data, income data, crop yield data, crop type data, rainfall data etc.
Vector
Vector is a data fromat commonly used to represent geographical features in GIS software. Spatial data can be represented and maintained as vector dataset in GIS. Vector datasets are generally represented as points, lines and polygons.
Raster
Raster is a GIS data format. It is used to represent features having continuous variation in the form of regular grids or pixels. Commonly used image formats such as jpeg, tiff, png, etc., can be considered as raster.
Latitude
The imaginary horizontal axis system used for pointing the locations on earth surface in the form of coordinates are called as latitudes. Latitudes vary from -90 to +90 degress from south to north of earth.
Longitude
The imaginary vertical axis system used for pointing the locations on the earth surface in the form of coordinates are called as longitudes. Longitudes vary from east to west.
Coordinate system
Projection system
Map
Geoid
Spheroid