We often feel difficulty to understand and visualize a problem just by seeing data or figures. We are more comfortable with visual representation of a problem that’s what GIS is giving to us (that too with the true representation of real-world).
GIS is made up of three terms- Geographic, Information and System. In literal meaning Geographic Information System is a System containing Information which is geographic in nature.
GIS can be defined as - A System which involves collecting/capturing, storing, processing. manipulating, analyzing, managing, retrieving and displaying data (information) which is, essentially, referenced to the real-world or the earth (i.e. geographically referenced).
Explanation of the Definition
We have used many term in the definition of GIS mentioned above. It is necessary to discuss each term for getting an idea - what actually GIS is?
The dataset collected for GIS may be in the form of hard copy maps, satellite images, survey data or other data obtained from other primary and secondary sources. Collection of data depends on the objective of the assignment. Data capturing involves digitization of hard copy maps and satellite images.
In GIS Storage means not merely storing whatever data we have collected. The collected data is converted in usable GIS format and then finally stored for further use either on computer hard disk or in other storage devices (CD, DVD, magnetic tapes etc.)
Processing and Manipulation
The collected and stored dataset is imported and converted into layers. Then required attributes are attached. Then data is processed for refinement, removing errors and preparing it for further GIS-based analysis. Data manipulation is essential so that it can be represented in proper understandable form.
Analysis of GIS data is required to convert it into desired outputs. There are many type of analysis in GIS which is (or are) to be done is objective dependant. The analysis may be statistical, spatial or specialized (like network analysis, utility analysis etc. Need not to say GIS analysis requires skilled professionals.
Data management is essential and very important part of GIS for storing, managing and properly maintaining GIS database.
In GIS, data can be retrieved through SQL or spatial queries. Some software provide tools to retrieve data by simply selecting the features. Retrieval is used for getting information about the features of our interest.
Displaying of final output may in many forms. These may be hard copy printouts, on-screen display of maps, internet-based map display (through Internet Map Servers) or in the form of presentation (like power point).