POLYGON DATA


An area completely bounded by one or more arcs. Polygons have shape and area characteristics. Each polygon is associated with one label point that relates to an attribute table. The entire area within the polygon is defined by the characteristics linked to the label point. All labels are uniquely numbered with an identifyer which relates to the attribute table.

The boundary of a polygon may be defined by natural phenomena, e.g. lakes or rivers, or by man e.g. forest stands, census zones

The arcs that form the polygon start and end with nodes. Where polygons meet, they share the same arc. The arcs that form the polygon have the same constructs as all other arcs namely nodes and vertices.

There are several types of areas that can be represented by polygons

ENVIRONMENTAL/NATURAL RESOURCE ZONES
 

Land cover data - forests, wetlands, urban

 
Geological data - rock types

 
Forestry data - forest "stands", "compartments"

 
Soil data - soil types

 
Boundaries are defined by the phenomenon itself

 
E.G. changes of soil type

 

SOCIO-ECONOMIC ZONES
 
Includes census tracts, zip codes, etc.

 
Boundaries may be culturally defined, e.g. neighborhoods

 

LAND RECORDS
 
Land parcel boundaries, land use, land ownership, tax information

 

HOLES AND ISLANDS
Areas often have "holes" or areas of different attributes wholly enclosed within them

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Go back to GER home pageAuthor: R. Douglas Ramsey Doug@nr.usu.edu