Overlaying Two Feature Sources
Concept Procedure Quick Reference
 
 
 

To perform an Overlay operation

  1. Connect to the features sources to compare.

    To use a feature layer, you must add it to your map. To use a feature class, you must connect to its data store, but you need not add it to the map.

  2. Analyze tabFeature panelFeature Overlay At the Command prompt, enter MapGisOverLay
  3. On the Overlay Analysis dialog box - Source and Overlay Type page, specify the following:
    • Source: Specify the feature layer or feature class to use as the source.

      For information about considerations in selecting Source and Overlay entries, see the Concept tab for this topic.

    • Overlay: Specify the feature layer or feature class to use as the overlay.
    • Type: Select the type of overlay comparison to perform. For more information on the available types, see the Concept tab for this topic.
  4. Click Next.
  5. On the Overlay Analysis dialog box - Set Output and Settings page, specify the following:
    • Output: Specify the name and location of the SDF file that will contain the result of the Overlay operation.
    • Layer Name: Specify the name of the Display Manager layer that will contain the result of the Overlay operation.
    • Sliver Tolerance: Specify which slivers become separate features and which are joined with a neighboring polygon. Set the units for the tolerance setting, then set the maximum and minimum values. To see recommended values, click Suggest. To ignore slivers altogether, click Don’t Remove Slivers.

      When the Overlay operation splits features to produce the output layer, it tries to eliminate polygons that are smaller than the specified tolerance settings. Such polygons might have been present in the sources, and some may be produced by the Overlay operation itself. The elimination of slivers affects the output layers only.

      Polygons that are larger than the Maximum value become separate features in the output layer. Polygons that are smaller than the Minimum value are merged with a neighboring polygon. The Overlay operation checks polygons that fall between the two values to see how wide they are. If they are very narrow, they are merged with a neighboring polygon.

      NoteIf the resulting polygons are not as desired, try adjusting the tolerance values and repeating the Overlay operation.
    • Ordinate Tolerance: Specify how far apart two nodes or vertices of a line or polygon must be to be treated as separate points in the output layer. Set the units for the tolerance setting, then set the Length.

      Any two points that are closer together than the Length value are treated as a single point in the output layer.

    • Output Properties: Specify which properties from the Source and (if applicable) Overlay are included in the resulting layer.

      “All” adds all properties to the resulting layer. “Identifiers” adds only the primary identifiers (primary keys or unique fields, such as Feature_ID). “Non-Identifiers” adds only the non-key attributes (such as Land_Value or Speed_Limit, for example). If you add only non-identifiers, the overlay operation generates primary identifiers for the features in the resulting layer.

  6. Click Finish to perform the Overlay.

    The Overlay operation creates a new layer representing the result of the comparison. The new layer is displayed in the map and in Display Manager. The same data is written to the SDF file you specified.

    To see just the Overlay output, deselect the check boxes for the other layers in Display Manager.