Constrained Thiessen Polygons

Purpose

Input features:
Output features:

The tool allows building Thiessen polygons from point features within the user defined boundaries. This way users may constrain output Thiessen polygons by other polygons.

Building constrained Thiessen polygons may be used for defining the accessibility (proximity) zones considering various natural, administrative or other boundaries. Analysis of potential customers location territories for a retail chain store based on its proximity within a state is the tool application example.

Description

Constrained Thiessen Polygons tool creates Thiessen polygons within the user defined constraining polygon features. If you build classic Thiessen polygons and then clip them by mask, the resulting Thiessen polygons won't be Thiessen polygons, but the Constrained Thiessen Polygons tool addresses this problem.

                Thiessen polygons cut by mask                                                               Constrained Thiessen polygons

Usage

• Select the "Constrained Thiessen Polygons" tool from the XTools Pro Analysis Tools.

• Select the input layer containing point features.

• Specify the name and location of the output feature class.

• Select the constraining polygon features.

• Specify ID field to store input features IDs.

• Press Run to build constrained Thiessen polygons.

Notes

• Input dataset can contain multipoint features as well.

• If input dataset contains duplicate features, Thiessen polygon will be built for one of them only.

• Input points located on bounds of constraining features won't be taken for building constrained Thiessen polygons.

• Constraining features can be multipart or adjacent, or have inner holes. But no constraining feature can have self-intersected borders.

• If constraining feature class contains intersected polygons or duplicates, output Thiessen polygons will be built separately for each constraining feature that includes input points.

• If there are no input points within the specified constraining polygons, the output polygon feature class will be empty.

• If constraining feature borders include arcs, it is recommended to densify them by another tool before running the "Constrained Thiessen Polygons" tool.

• In rare cases, when the constraining features have too complicated geometry or special shape, building the constrained Thiessen polygons may be impossible.

In this special case constrained Thiessen polygons won't be built.