Introduction to Geographic Information System (GIS)

A Geographic Information System (GIS) is a computer system that geographically analyses and displays referenced information. It uses data that is attached to a unique location. Most of the information we have about our world contains a location reference. For example Information about places on the Earth’s surface, knowledge about “what is where when. Do not forget the time!

Geographic Information Systems (GIS) is the common ground between information processing and the many fields using spatial analysis techniques (Tomlinson, 1972). It is a robust set of tools for collecting, storing, retrieving, transforming, and displaying spatial data from the real world (Burroughs, 1986); A computerized database management system for the capture, storage, retrieval, analysis, and display of spatial (locationally defined) data; A decision support system involving the integration of spatially referenced data in a problem-solving environment (Cowen, 1988).

Geographic Information Technologies are technologies that deal with GIS information. Generally, there are three of these technologies:

I. Global Positioning Systems (GPS) – a system of earth-orbiting satellites that can provide precise (100 meters to sub-cm.) location on the Earth’s surface (in lat/long coordinates or equivalence)

II. Remote Sensing (RS) uses satellites or aircraft to capture information about the Earth’s surface. Digital orthoimages are a crucial product (map-accurate digital photos).

III. Geographic Information Systems (GIS) – Software systems with the capability for input, storage, manipulation/analysis, and output/display of geographic (spatial) information

In summary, GPS and RS are sources of input data for a GIS. A GIS provides for storing and manipulating GPS and RS data.

References:

Burrough, P. A., 1986. Principles of Geographical Information Systems for Land Resources Assessment. Oxford University Press, N.Y. 193 p.

Cowen, D. J. 1988. GIS versus CAD versus DBMS: What are the differences? Photogrammetric Engineering and Remote Sensing 54:1551-1554.

Tomlinson, R. F. (1972) Geographical Data Handling (volume 2). International Geographical Union Commission on Geographical Data Sensing and Processing for UNESCO/IGU, 2nd. Symposium on Geographical Information Systems, Ottawa, 1-9 August, 1972