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Geographic Information System

Geographic Information System (GIS)


Geographic Information System (GIS) is a computer based database system for capturing storing analysis and presentation of geographic data (Chorley Report, 1987 pp3). Geographic data is data that relates to points on or above the surface of the earth that has both positional information and attributes information. GIS composes of the following fields, cartography, CAD, photogrammetry, spatial analysis and remote sensing. The integration of the above multiple fields in several initially separate but closely related fields has lead to linking of various forms of data resulting in truly general purpose GIS.

GIS identifies data in the real world in the following terms:
-The position of the data with respect to a known reference system
-The spatial relations of the data in relation to other data.

GIS use in storing data can best be summed up in the following quote former American Vice President Al Gore:
"A new wave of technological innovation is allowing us to capture, store, process and display an unprecedented amount of information about our planet and a wide variety of environmental and cultural phenomena. Much of this information will be 'geo-referenced' – that is, it will refer to some specific place on the Earth's surface. The hard part of taking advantage of this flood of geospatial information will be making sense of it, turning raw data into understandable information."

Data in a GIS should be thought of representing a model of the world. Ideally GIS is a representation of aspects of the earth in a known reference system such that the position of a feature on the ground has the same coordinates as the same feature in a GIS database. These data can be accessed, transformed, manipulated and interactively analyzed such that it can be used to study the Earth and all the processes that keep the Earth the way it is.

GIS can be used by planners and decision makers to explore a range of possible scenarios and obtain ideas about possible consequences of a cause of action. Components of a GIS include, data input and verification, data storage and management, data output and presentation, and data transformation (Gilberto, 1995, pp 6).

Data in a GIS can be capture in the following ways :
-land survey records
-remote sensing imagery
-aerial photos
-existing maps

Data collection by remote sensing is the cheapest of the above modes of data capture considering the cost of imputing and verifying the data for large areas is very high. GIS is a very

powerful tool for data capture although it is very expensive because of the cost of software, hardware, data collection, capture and processing. Infact it has been estimated that the cost of data consumes about 50% of budget of setting up a GIS system (Williams, 1987, pp 151).

GIS has many advantages over conventional methods of data storage. These include:
• Larger storage space.
• Data maintains it integrity in a GIS than other methods.
• Fast retrieval of Data.
• Overlaying of data in GIS is much easier than in other methods.

GIS can be applied in various fields like, business, agriculture, crime management, town planning, mapping, and designing.



WORKS CITED

Camara, Gilberto, Monteiro, Antonio Miguel Vieira, and Onsrud, Harlan, "GIS as Appropriate Technology: Research and Applications in Brazil", working paper, 1995.

Chorley Report. "Handling geographic information; GIS research agenda; state of the GIS industry; societal impact of GIS" 1987. pp3

Former American Vice-President "New Technology Talk" 1998

Robert P. Biuk-Aghai "Macau Map: Tourism-Oriented Mobile GIS Application", Map Asia 2003 < http://www.gisdevelopment.net/technology>

Posted by: Christie Ingram

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