In this example you saw how to create a Map Topology. Before you create a map topology, it is a good idea to zoom in to the area that you want to edit. Zooming in to an area reduces the number of features that the map topology analyzes when building the topology cache.

Map topologies can be created with ArcView licensed seats of ArcMap, and can be used with geodatabase and shapefile features.

When you click the Map Topology button during an edit session, the Map Topology dialog box appears. You can select the feature classes that will participate in the topology and choose a cluster tolerance. The cluster tolerance defines how close together parts of features must be before they are considered to be coincident.

In this example, you want all of the features on the map from both feature classes to participate in the map topology. The default cluster tolerance is the minimum possible cluster tolerance and is given in coordinate system units. In this case the dataset is in the Universal Transverse Mercator coordinate system, and the units are meters. You will accept the default cluster tolerance.

When you click the Topology Edit tool and click a line or the boundary of a polygon, the features in the current extent are analyzed to identify topology edges and nodes. The edge you click is selected and changes color. If you have set ArcMap to show unselected topology nodes, then open circles will also appear around the intersections of the lines that make up the polygon edges. These are unselected nodes in the map topology.

In this example, the edge that was clicked is shared by the larger regional polygons and the smaller local watershed polyons.