Create Thiessen Polygons (Analysis) (ArcInfo only)

Usage tips

• Thiessen polygons can be used to apportion a point coverage into polygons known as Thiessen or Voronoi polygons. Each polygon contains only one Input Features point. Each polygon has the unique property that any location within the polygon is closer to the polygon's point than to the point of any other polygon.

• The Thiessen polygons are constructed as follows:

  All points are triangulated into a triangulated irregular network (TIN) that meets the Delaunay criterion.
  The perpendicular bisectors for each triangle edge are generated, forming the edges of the Thiessen polygons. The location at which the bisectors intersect determine the locations of the Thiessen polygon vertices.

• The outside boundary of the Thiessen polygons is the extent of the points used plus an additional 10%. If the Extent environment is set to a specific set of values, CreateThiessenPolygons will use the environment to set its outside boundary.

• The following environments affect this tool: configKeyword, extent, MDomain, outputCoordinateSystem, outputMFlag, outputZFlag, scratchWorkspace, spatialGrid1, spatialGrid2, spatialGrid3, workspace, XYDomain, and ZDomain.

Command line syntax
An overview of the Command Line window
CreateThiessenPolygons_analysis <in_features> <out_feature_class> {ONLY_FID | ALL}

Command line example

createthiessenpolygons c:\basedata\wells.shp c:\analysis\thiessen_wells.shp ALL

Scripting syntax
About getting started with writing geoprocessing scripts
CreateThiessenPolygons_analysis (in_features, out_feature_class, fields_to_copy)

Script example

import arcgisscripting
gp = arcgisscripting.create()

gp.workspace = "c:/basedata"
gp.toolbox = "analysis"

gp.createthiessenpolygons("wells.shp", "thiessen_wells.shp", "ONLY_FID")