Geographic information system

  • 14 сент. 2010 г.
  • 7230 Слова
Geographic information system

A geographic information system (GIS), or geographical information system, is any system that captures, stores, analyzes, manages, and presents data that are linked to location. In the simplest terms, GIS is the merging of cartography and database technology. GIS systems are used in cartography, remote sensing, land surveying, photogrammetry, geography, urbanplanning, emergency management, navigation, and localized search engines.
As GIS is a system, it has boundaries that may be jurisdictional, purpose or application oriented for which a specific GIS is developed. Hence, a GIS developed for an application, jurisdiction or purpose may not be necessarily interoperable or compatible with a GIS that has been developed for some other application,jurisdiction or purpose. What goes beyond GIS is spatial data infrastructure (SDI), a concept that has no such restrictive boundaries.
Therefore, in a general sense, the term describes any information system that integrates, stores, edits, analyzes, shares, and displays geographic information. In a more generic sense, GIS applications are tools that allow users to create interactive queries (user-createdsearches), analyze spatial information, edit data, maps, and present the results of all these operations. Geographic information science is the science underlying the geographic concepts, applications and systems, taught in degree and certificate programs at many universities.


GIS technology can be used for scientific investigations, resource management, asset management,archaeology, environmental impact assessment, urban planning, cartography, criminology, geographic history, marketing, logistics, prospectivity mapping, and other purposes. For example, GIS might allow emergency planners to easily calculate emergency response times (i.e. logistics) in the event of a natural disaster, GIS might be used to find wetlands that need protection from pollution, or GIS can beused by a company to site a new business location to take advantage of a previously under-served market.

History of development

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. His study of the distribution of cholera led to the source of the disease, a contaminatedwater pump (the Broad Street Pump, whose handle he had disconnected, thus terminating the outbreak) within the heart of the cholera outbreak.

E. W. Gilbert's version (1958) of John Snow's 1855 map of the Soho cholera outbreak showing the clusters of cholera cases in the London epidemic of 1854
While the basic elements of topography and theme existed previously in cartography, the John Snow map wasunique, using cartographic methods not only to depict but also to analyze clusters of geographically dependent phenomena for the first time.
The early 20th century saw the development of photolithography, by which maps were separated into layers. Computer hardware development spurred by nuclear weapon research led to general-purpose computer "mapping" applications by the early 1960s. The year1962 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 effort to determine the land capability forrural 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 such system and an improvement over "mapping" applications as it provided capabilities for overlay, measurement, and digitizing/scanning. It supported a national...