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How To: Use Geoprocessing tools to create line features from polygon outlines that can be symbolized as cased or dashed

Summary

Instructions provided describe how to symbolize polygon outlines with either a cased line (a line with fill color and a different outline color), or a dashed/dotted line in ArcGIS 9.

When symbolizing polygon outlines, problems arise when choosing cased line or dashed/dotted line symbology. This is because when polygons are drawn, the shared edge between two polygons is drawn twice. The effect when choosing cased outlines is that lines do not intersect well. The effect when choosing dashed or dotted lines is irregular and overlapping dash or dot patterns.

Procedure

The 'Polygon to Line' Geoprocessing tool (under Data Management Tools / Features) prepares the polygon outlines for symbolizing with cased or dashed/dotted lines.

[O] Example of cased and dashed polygon outlines

Note:
In ArcGIS 8.3 and later versions, you can also use topology to prepare polygon outlines for symbolizing with cased or dashed/dotted lines. See the Related Information section below to learn more about this method.

  1. Start ArcMap.
  2. Add the polygon feature class, shapefile or coverage to the map.
  3. Convert the polygon to a polyline.
    A. Start ArcToolbox.
    B. Navigate to Data Management Tools\Features\Polygon to Line.
    C. Select the polygon feature to be converted from the input drop down list.
    D. Verify the output file name and location.
    E. Click OK.

    Note:
    The output line feature class will have two attribute fields: LeftID and RightID, populated with the Object ID of the source polygons. Though the tool does not provide an option to transfer any additional original polygon attributes, you can use the right and left ID fields to have access to additional attributes through joins or relates.

  4. Double-click on the line layer symbol in the Table of Contents. Choose a cased or dashed/dotted line and click OK.
  5. If symbolizing the lines as cased, right-click on the layer in the Table of Contents and choose 'Use Symbol Levels'. This activates advanced Symbol Level drawing for the layer, which allows the case polygon outlines to connect nicely.

    Additional changes can be made to Symbol Levels from the Layer properties dialog, Symbology tab. Click the Advanced button, then choose Symbol Levels.

Related Information