Geographical Information System (GIS) , an Information System which deals with geography, Most of you know what is an information system is - a computer based technology for retreiving, storing, organising and analysing data. When we add geographic component i.e location to an information system it is called a Geographical Information System. Location of any particular data can be the x,yand z of the data or latitude, longitude and altitude of the data.
A simple definition on GIS "Computer-based technology for retreiving, storing organising and analysing data based on its location (X,Y,Z) on a digital map."
A digital map is nothing but digitised paper map for computer usage . There are two ways of representing digital maps in GIS
vector
- points (e.g. ATM location), lines (e.g. road), Polygons
(e.g. buildings) - CAD drawings are Vector
Raster
- Space subdivided into Cells/Pixels - Scanned Images are raster
A GIS handles Spatial information and help you to retrive or query with respect to location.
" Show all primary schools within 2 km from my home" - Such queries can be handled only by a GIS
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A working GIS integrates following components: hardware, software, data, people, and methods.
Hardware and Software
Hardware is the computer on which a GIS operates. Today, GIS software runs on a wide range of hardware types, from centralized computer servers to desktop computers used in stand-alone or networked configurations, including internet.
GIS software provides the functions and tools needed to store, analyze, and display geographic information. Key software components are
Geographic data, or “geodata”, are data that describes phenomena directly or indirectly associated with a location (and time, and orientation) relative to the surface of the Earth. Two types of geodata can be found in a GIS system : Spatial data and attribute data.
A Map is good example of representing spatial data. But spatial data can any data with a location component. The location component could be the addresses of customers or suppliers, the course of a river and the outline of its floodplain, the locations of thousands of utility poles, or X and Y coordinates on a blueprint. Spatial data is not limited to the land surface but includes the subsurface, aquatic, marine, and lower atmospheric regions.
Attributes are characteristics of a geographic feature described by numbers, characters typically stored in tabular format and linked to the feature by a user-assigned identifier (e.g., the attributes of a well might include depth and gallons per minute).
These two types of geodata can be collected in-house or purchased from a commercial data provider. A GIS will integrate spatial data with attribute data and can even use a DBMS to manage spatial data.
People and Methods
GIS
technology is of limited value without the people who manage the system
and develop plans for applying it to real-world problems. GIS users range
from technical specialists who design and maintain the system to those
who use it to help them perform their everyday work.
A
successful GIS operates according to a well-designed plan and business
rules, which are the models and operating practices unique to each organization.
A geographic information system (GIS) capture and store spatial data with the help of geographic mapping capabilities. It includes the actual geometry of objects i.e shape, size, location (for example a building or a road ), related text attributes for each object for analysis purposes (for example, customer name and address for each location), and an engine that interprets and manipulates spatial geometry.
A GIS knows how to determine all locations in its database that are within a specified distance of another location, or whether two roads intersect. A GIS also provides robust data-visualization and analysis tools, enabling users to view their data in completely new ways. Instead of receiving a list of stores and their addresses, the user sees a map in color with store locations identified. The map may also display other information, such as major highways, to enhance the user’s analytical context.
The big players in GIS industry are:
A quick analysis by the Author - It is always a dilemma to the end user to decide on which GIS software to buy. Choosing the correct software is important to the success of any GIS project. All the above GIS products support most of the GIS functionalities. It is noted that all GIS projects are unique by the nature , and selecting a GIS software depend on the particular project need.
Arc/Info has very good GIS capability, MGE is good in GIS data capture and maintenance, AutoCAD map is easy to use, MapInfo and ArcView are excellent desk top mapping software and Geomedia is a Universal GIS client , can on line read different GIS .
Because of the emergence of Internet , advances in Database management system and international effort on arriving GIS standards , GIS is no more a specialist domain but becoming a part of mainstream IT.
Web GIS - Browser based GIS using Web protocols and need only Plug in to handle GIS data types . e.g ARC IMS from ESRI, Geomedia Web Map from Intergraph.
Spatial DBMS -Extension of RDBMS to store multi dimensional
geographical data. This will help GIS vendors/users to focus on application
and leverage on RDBMS strong data management capabilities. e.g Oracle Spatial
Catridge from Oracle, Informix Universal Data Server from Informix, DB2
Spatial Extender from IBM.
