Definitions of Geographic Information System(GIS)

GEOGRAPHIC INFORMATION SYSTEM

DEFINITIONS OF GIS

The tool-base definition of a GIS is 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 purpose.

(a) Toolbox - based definitions

A powerful set of tools for collecting, storing, retrieving at will, transforming and displaying spatial data from the real world. A system for capturing, storing, checking, manipulating, analyzing and displaying data which are spatially referenced to the Earth. An information technology which stores, analyses, and displays both spatial and non-spatial data.

b) Data base definitions

A database system in which most of the data are spatially indexed, and upon which a set of procedures operated in order to answer queries about spatial entities in the database. Any manual or computer based set of procedures used to store and manipulated geographically referenced data.

c) Organization - based definitions

An automated set of functions that provides professionals with advanced capabilities for the storage, retrieval, manipulation and display of geographically located data.

1 DEVELOPMENT OF GEOGRAPHICAL INFORMATION SYSTEMS

In the late twentieth century, demands for data on the topography and specific themes of the earth's surface, such as natural resources, have accelerated greatly. Stereo aerial

photography and remotely sensed imagery have allowed photogrammetrists to map large areas with great accuracy. The same technology also gave the earth resource scientists - the geologist, the soil scientist, the ecologist, the land use specialist - enormous advantages for reconnaissance and semi - detailed mapping.

The need for spatial data and spatial analyses is not just the preserve of each scientists.

Urban planners and cadastral agencies need detailed information about the distribution of land and resources in towns and cities.

Civil engineers need to plan the routes of roads and canals and to estimate construction costs, including those of cutting away hillsides and filling in valleys. Police departments need to know the spatial distribution of various kinds of crime, medical organizations

Epidemiologists are interested in the distribution of sickness and disease, and Commerce as interested in improving profitability through the optimization of the distribution of sales outlets and the identification of potential markets.

The enormous infrastructure of what are collectively known as ?utilities'-that is water, gas, electricity, telephone lines, sewerage systems - all need to be recorded and manipulated as spatial data linked to maps.

About 15,500 years ago on the walls of caves near Lascaux, France, Cro-Magnon hunters drew pictures of the animals they hunted. Associated with the animal drawings are track lines and tallies thought to depict migration routes.

In 1854, John Snow depicted a cholera outbreak in London using points to represent the locations of some individual cases, possibly the earliest use of the geographic method.^[4] His study of the distribution of cholera led to the source of the disease, a contaminated water pump (the Broad Street Pump, whose handle he disconnected terminating the outbreak) within the heart of the cholera outbreak.

The year 1967 saw the development of the world's first true operational GIS in Ottawa, Ontario, Canada by the federal Department of Forestry and Rural Development. Developed by Dr. Roger Tomlinson, it was called the "Canada Geographic Information System" (CGIS) and was used to store, analyze, and manipulate data collected for the Canada Land Inventory (CLI)-an initiative to determine the land capability for rural Canada by mapping information about soils, agriculture, recreation, wildlife, waterfowl, forestry, and land use at a scale of 1:50,000. A rating classification factor was also added to permit analysis.

CGIS was the world's first "system" and was an improvement over "mapping" applications as it provided capabilities for overlay, measurement, and digitizing/scanning. It supported a national coordinate system that spanned the continent, coded lines as "arcs" having a true embedded topology, and it stored the attribute and locational information in separate files. As a result of this, Tomlinson has become known as the "father of GIS," particularly for his use of overlays in promoting the spatial analysis of convergent geographic data CGIS lasted into the 1990s and built the largest digital land resource database in Canada. It was developed as a mainframe based system in support of federal and provincial resource planning and management. Its strength was continent-wide analysis of complex datasets. The CGIS was never available in a commercial form.

By the early 1980s, M&S Computing (later Intergraph), Environmental Systems Research Institute (ESRI) and CARIS (Computer Aided Resource Information System) emerged as commercial vendors of GIS software, successfully incorporating many of the CGIS features, combining the first generation approach to separation of spatial and attribute information with a second generation approach to organizing attribute data into database structures. In parallel, the development of two public domain systems began in the late 1970s and early 1980s. MOSS, the Map Overlay and Statistical System project started in 1977 in Fort Collins, Colorado under the auspices of the Western Energy and GRASS GIS was begun in 1982 by the U.S. Army Corps of Engineering Research Laboratory (USA-CERL) in Champaign, Illinois, a branch of the U.S. Army Corps of Engineers to meet the need of the United StatesMilitary for software for land management and environmental planning. The later 1980s and 1990s industry growth were spurred on by the growing use of GIS on Unix workstations and the personal computer. By the end of the 20th century, the rapid growth in various systems had been consolidated and standardized on relatively few platforms and users were beginning to export the concept of viewing GIS data over the Internet, requiring data format and transfer standards. More recently, there are a growing number of free, open source GIS packages which run on a range of operating systems and can be customized to perform specific tasks.