What is Geographic Information System?

Geographic Information System (GIS) is a computer based information system capable of digitally representing and analyzing geographic features and events. The main purpose of GIS involves assembling, storing, manipulating and displaying data in a database that is identifiable according to locations, with a view that every object on the earth's surface can be easily geo-referenced. Geographic Information Systems works on the simple premises that almost every form of data can be related to a map or other forms of easily understandable graphics. Data from GIS is available in the form of maps, 3D virtual models, tables or lists (maps are however the most common form of output).

A complete Geographic Information System typically comprises of the following:

• Computer Hardware and other required peripherals
• Software
• Data
• People to feed in data and to interpret information
• Comprehensive Training to make effective use of system

GIS may be a complex system involving dedicated databases and workstations connected to a network or it may be a simple desktop software.

Data Representation and Projection in GIS

GIS represents real world data (both discrete objects and continuous fields) using digital data. If data exists in ordinary form then a digitizer, scanner, etc, may be used to convert coordinates in to digital format. While inputting data in to the GIS one needs to specify identities of the objects on the map as well as their spatial relationships. Data representation in Geographic Information System is done using following methods:

• Raster Method - Here data is arranged in rows and columns or in the form or cells storing single values. Value recorded in each cell may be categorized on basis of individual data classes that they represent.
• Vector Method - Geometries such as points, lines, areas, etc, are used to represent objects. You can also make use of vectors to represent continuously varying fields.

GIS uses principal of mathematical projection while transferring information from one model to another (from three-dimensional curved surfaces to two-dimensional mediums such as paper or computer).

How to relate information using GIS?

Primary purpose for employing Geographic Information System is to relate information across different sources. For this purpose it is essential to know locations of the different variables that needs to be related. The system uses random notations such as x, y, z in order to denote location of the different variables under study. These variables may be coordinates of latitude, longitude and elevation or they may be other geocode system like Zip codes, highway mile markers, etc. Several government and non-government agencies are coming up with computer databases that can be directly entered in to GIS.

Take a look at few advantages of using GIS:

One can make use of Geographic Information System to accomplish effective spatial analysis with data collected from different information points. Results from such an analysis can help to build a cause-and-effect relationship or can provide valuable solutions to a wide array of problems depending on purpose for which GIS is employed.

GIS may be used to determine rainfall amounts wherein two-dimensional and three-dimensional information relating to earth's surface, subsurface and atmosphere are collected across information points to obtain the required resultant map information. This rainfall information (in different states) when related with respective aerial photographs of the county helps determine which wetlands dry up at certain times of the year (or such other information as may be required). Another area where Geographic Information System is popularly used is in the police and fire departments. Here GIS helps to locate landmarks and hazards, plot destinations and also helps to design emergency routes.

Today engineers, planners and managers make use of Geographic Information System in almost all business areas (including Government, Academic, and Commercial levels. GIS is considered as an efficient tool to help carry out organization and administration of industry database (pertaining to geographic information or other relating details) and to implement effective database management and analysis. Scientists are these days working towards improving use of GIS in remote sensing to obtain more accurate results.