How To: Delete overlapping sections of polygons based on a field
In some instances, when working with large volumes of multiple overlapping polygons, attempts to isolate and delete specific overlapping sections of polygons based on a specific field can be tedious and time consuming. For example, attempting to isolate specific polygons from a shapefile containing many overlapping polygons.
At the Advanced license level, the Eliminate Polygon Part tool is available. For more information, refer to ArcGIS Help: Eliminate Polygon Part. However, at the Basic and Standard licensing level, the Eliminate Polygon Part tool is not available, use the Dissolve tool instead.
The following steps describe how to delete overlapping sections of polygons based on a field using the Dissolve tool:
Note: This workflow describes the use of shapefiles. If a file geodatabase feature class is used, the join includes duplicate records.
- In Table of Contents, right-click the original polygon shapefile > Open Attribute Table.
- Create a new Text field for storing unique ID values.
- While in an Edit Session, right-click the newly created unique ID field and select the Field Calculator.
- Select two or more fields from the original polygon shapefile, and use the '&' operator to populate the field with unique values > click OK.
The unique ID value is the identifier that distinguishes the specific field for the Dissolve tool to remove.
- Navigate to ArcToolbox > Data Management Tools > Generalization > Dissolve.
- For Input, select the desired polygon shapefile.
- For Output, ensure that a folder is selected, not a geodatabase. Selecting a folder for Output creates a new shapefile for the dissolved polygon.
- Specify the fields to dissolve.
- Optionally, select the desired statistical fields.
- Click OK.
- Repeat Steps 2 through 4 with the output of Step 5.
Note: Ensure the two fields selected in the Field Calculator for the new shapefile are identical to the fields selected in Step 4 the original polygon shapefile.
- Create a new table join between the original shapefile and the newly created shapefile output from the Dissolve tool using the unique ID field from Step 2. For more information on joining attributes between tables, refer to the following documentation, ArcGIS Help: Joining attributes in one table to another.
- Right-click the layer in the Table of Contents > Data > Export data to make the join permanent. The overlapping sections of polygons are now deleted according to the user defined criteria.
- ArcGIS Help: How Dissolve (Data Management) works
- ArcGIS Help: Using the Calculate Field tool
- ArcGIS Help: Dissolve
- ArcGIS Help: How Eliminate (Coverage) works