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Thread: Specifying a number of points per new polygon

  1. #1
    Paul McKenzie
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    Default Specifying a number of points per new polygon

    I have a point layer that contains an attribute of severity scores. I want to create a new polygon layer that contains a specific number of points per polygon. I would ideally like the polygon to enclose the points with the severity scores in descending order. However I would settle for a tool that created new polygons based on a user specified number of points i.e. each polygon contains approx 100 points.

    Any help greatly appreciated,

    Paul

  2. #2
    Dan Lee

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    Default Re: Specifying a number of points per new polygon

    Could you clarify whether you want polygons to spatially CONTAIN (enclosing) points; or to use the points to construct polygons - meaning to use the points as vertices on the polygon boundaries? You can post screen images to show your data and expected results.

    What version of ArcGIS are you using?
    Dan (Geoprocessing)

  3. #3
    Paul McKenzie
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    Default Re: Specifying a number of points per new polygon

    Dan

    Thanks for coming back to me so quickly.

    I want the new polygons to spatially CONTAIN (enclosing) points yes. That means that a new polygon is created that will contain a specified number of points. If you need further clarification I can do a mock up and send a screen shot.

    I currently use ArcGIS v. 10.0 but have access to 9.3 and also 3.2 if necessary.

    Many thanks,

    Paul

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    Dan Lee

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    Default Re: Specifying a number of points per new polygon

    Thanks for the clarification. I am still not clear what you meant by "I would ideally like the polygon to enclose the points with the severity scores in descending order". Did you want points of the same severity score be in the same polygon? Who does the "descending order come to play? You also mentioned about 100 points per polygon; how do you expect them to be selected or grouped - based on cluster distance or attribute?

    The following two tools can be used to produce polygons from points:

    1. Minimum Bounding Geometry (Data Mangement toolbox - Features toolset; new in ArcGIG 10). It has several bounding geometry types and a parameter, Group Option, for grouping based on attribute field(s). Please refer to the help topic to see what geometry types are availale at ArcView level and higher levels.
    http://help.arcgis.com/en/arcgisdesk...000003q000000/

    2. Aggregate Points (Cartography toolbox - Generalization toolset; new in ArcGIS 10). This tool creates polygons from points based on cluster distance. The polygon shapes can be "concave" in contrast to "bounding".
    http://help.arcgis.com/en/arcgisdesk...000002s000000/

    Hope you can use one of the above.
    Dan (Geoprocessing)

  5. #5
    Paul McKenzie
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    Default Re: Specifying a number of points per new polygon

    Dan

    Thank you very much for these two links - it looks like the first tool for minimum bounding geometries is what I need. Unfortunately I don't have an ArcInfo license! I will see what I can do. Thanks again for your time and help,

    Paul

  6. #6
    Dan Lee

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    Default Re: Specifying a number of points per new polygon

    Paul,

    The RECTANGLE_BY_AREA and RECTANGLE_BY_WIDTH options are available for ArcView license, in case you didn't notice. Could these options work for your analysis?
    Dan (Geoprocessing)

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