Document: Creating Island/Donut Polygons in ArcGIS
Created: 10/7/2004 (Tom Evans)

Summary

Sometimes it may be necessary to create new polygons with interior holes, or cut holes out of existing polygons. For example, a lake feature could be represented as a polygon without including islands as part of the lake's area. These holes in polygons can be created with the Sketch tool by digitizing an interior ring as a second part of the polygon shape.

This document describes how to create island polygons in ArcGIS ArcEditor. As with many GIS operations, there are multiple methods of accomplishing this task. Here are some:

Procedure 1 (use this method with Geodatabase files):

In ArcMap, select Editor > Start Editing.

  1. From the Task dropdown menu, select Create New Feature.
  2. To cut a hole out of an existing polygon, click the Edit tool and double-click the polygon to see the Edit sketch.

    To create a new polygon with a hole in it, click the Sketch tool and digitize the outer edge of the new polygon from which you want to remove a part.

  3. Right-click on the edit sketch of the exterior of the polygon and click Finish Part.
  4. Digitize the area within the polygon that will not be included in the larger, exterior polygon. When cutting a hole from an existing polygon, it is necessary to select the Sketch tool first.
  5. Right-click and click Finish Sketch. The hole is removed from the area of the exterior polygon.

Procedure 2:

An alternative method (suitable for working with datasets in the Coverage format) involves creating interior and exterior polygons as separate entities, adding an attribute field to code items as either island or non-island polygons, and then setting the attributes for individual features.