History of GIS

Mapmaking (representation of geographical information) has evidences to show independent evolution of maps in different parts of the earth. The direct evidence of mapping comes from Middle East in the form of Babylonian Clay Tablets as early as 1000 B.C which depicted earth as a flat circular disk.

Around 200 B.C, Eratosthenes calculated the circumference of earth accurately. Later came, Ptolemy and Al-Idrisi who made remarkable contributions in the field of cartography. Following them were Mercator and Newton, their work paved way for the upcoming cartographers and geographers to better understand the earth and the geographical phenomenon.

Putting layers of data on series of base maps to analyze things geographically has been into existence much longer than the introduction of computers to the geographical world.

The French cartographer Louis-Alexandre Berthier had drawn the maps of the Battle of Yorktown (1781) that contained hinged overlays to show troop movements.

(Image source: http://findingaids.princeton.edu/getEad?eadid=C0022 )

Superimposition of topography, geology, population and traffic flow on the same base map has been shown in the Atlas to Accompany the Second report of the Irish Railway Commissioners.

Dr. John Snow showed the locations of death by cholera on a map to track the source of outbreak of cholera in Central London in September, 1854.

(Image source: http://healthcybermap.org/HGeo/pg1_1.htm )

The introduction of computers in the field of geography was a positive step towards understanding and learning the subject better. Change in cartographic analysis due to improved graphics, development of theories of spatial processes in economic and social geography, anthropology and regional science, increased social awareness and improvement in education. The integrated transportation plans of Detroit, Chicago during the period of 1950s and 1960s used information on routes, origin, destination, and time to produce the maps of traffic flow and volume is an example of integration of computer technology with geographical data.

Introduction to GIS

GIS stands for Geographical Information System. It is defined as an integrated tool, capable of mapping, analyzing, manipulating and storing geographical data in order to provide solutions to real world problems and help in planning for the future. GIS deals with what and where components of occurrences. For example, to regulate rapid transportation, government decides to build fly-over (what component) in those areas of the city where traffic jams are common (where component).

GIS means differently to different people and therefore has different definitions. For example, Burrough (1998) defined GIS as “ a powerful set of tools for collecting, storing, retrieving at will, transforming and displaying spatial data from the real world for a particular set of purposes”

Objectives of GIS

Some of the major objectives of GIS are to

Maximizing the efficiency of planning and decision making Integrating information from multiple sources Facilitating complex querying and analysis Eliminating redundant data and minimizing duplication

Components of a GIS

A GIS has following components:

Hardware : It consists of the equipments and support devices that are required to capture, store process and visualize the geographic information. These include computer with hard disk, digitizers, scanners, printers and plottersetc.

Software : Software is at the heart of a GIS system. The GIS software must have the basic capabilities of data input, storage, transfosrmation, analysis and providing desired outputs. The interfaces could be different for different softwares. The GIS softwares being used today belong to either of the category –proprietary or open source. ArcGIS by ESRI is the widely used proprietary GIS software. Others in the same category are MapInfo, Microstation, Geomedia etc. The development of open source GIS has provided us with freely available desktop GIS such as Quantum, uDIG, GRASS, MapWindow GIS etc., GIS softwares.

Data : The data is captured or collected from various sources (such as maps, field observations, photography, satellite imagery etc) and is processed for analysis and presentation.

Procedures : These include the methods or ways by which data has to be input in the system, retrieved, processed, transformed and presented.

People : This component of GIS includes all those individuals (such as programmer, database manager, GIS researcher etc.) who are making the GIS work, and also the individuals who are at the user end using the GIS services, applications and tools.