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A Geographic Information System, or GIS, is a computer-based approach
to collecting, storing, and analyzing data that have spatial characteristics.
A GIS can be thought of as a collection of electronic maps, stored in
a computer database, that allows a wide range of analysis and product
generation.
A GIS stores data
that are primarily geographical in nature. Geography, as defined by
Webster's University Dictionary, is the study of the earth and its features
and the distribution of life on the earth. A GIS stores information
about these subjects including the location and other detailed descriptions
or attributes. Capturing and storing the location of things or events
on the surface of the earth allows the GIS to display and analyze spatial
relationships.
The spatial locations
in a GIS are simply defined by X,Y coordinates such as latitude and
longitude. Spatial locations can show where the features are located
and also define the shape of the feature. Geographic data usually have
one of three basic forms; a point, a line, or a polygon. Points have
a single coordinate location and can represent a feature such as a bird
nest. Lines have a starting and ending location, and points in between
that describe their shape. A stream or highway may be represented in
the GIS as a line. The last shape data can take is a polygon. A polygon
is formed when a line defines a closed shape. Examples of polygon features
include lakes or real estate parcels. For more information on GIS, see www.gis.com.
OTHER GIS MAPPING
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