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GIS Defined

The maturation of the computer age has greatly changed the manner in which multiple maps and other data sets can be merged, compared and otherwise manipulated. Both handling capacity and flexibility can be significantly enhanced. A powerful new tool, known as the Geographic Information System (usually, once stated, thereafter referred to by its common acronym of GIS) emerged in the 1970s. Many of those who developed GIS were inspired by the classic 1969 publication of Design with Nature by Ian McHarg (Doubleday/Natural History Press), a leading landscape architect then at the University of Pennsylvania, which pointed the way to planning and decision-making through use of comparative, integrated maps and related data types. Since its inception, GIS has become a major growth industry now conducted worldwide at the multi-billion dollar level. It has blossomed into the main way now by which maps are put to novel and practical uses in most endeavors that focus and rely on geographically-based data of many kinds. As remote sensing has routinely provided new images of the Earth's surface, it too has become intertwined with GIS as a means to constantly and inexpensively update some of the data (such as land use and cover) that comprise an integral segment of a GIS.

GIS has been defined by the Association for Geographic Information as:

A system for capturing, storing, checking, integrating, manipulating, analyzing, and displaying data which are spatially referenced to the Earth.

A simpler working definition: A computer-based approach to interpreting maps and images and applying them to problem-solving.

The role of GIS in the general planning process for site selection, environmental managing, and other geographically-dependent applications is synopsized in this diagram:

From B. Davis, GIS: A Visual Approach, ©1996. Reproduced by permission of Onword Press, Santa Fe, NM.

The driver for this closed-loop operation is the constant need for timely information about human activities and expectations concerning life in the "real world". The specifics underlying those needs define the types and amounts of data/information required. Once stipulated, the data are collected from multiformed sources, such as already published maps and tabulations, current field observations, surveys, and aerial/satellite imagery. The next step involves conversion of varied data into computer-compatible formats. The heart of the GIS operation lies within various techniques for analysis that have been devised with the evolution of GIS itself. Reports, displays, new maps, statistics and other kinds of computer-based information-oriented products are then presented as output to the decision-makers for judicious utilization. The test of value is then conducted by application of the results in the same real world that dictated initial requirements. Data management through a GIS involves all of these facets:

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Code 935, Goddard Space Flight Center, NASA
Written by: Nicholas M. Short, Sr. email: nmshort@epix.net
and
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Updated: 1999.03.15.