Masking feature representations
This topic applies to ArcEditor and ArcInfo only.
Masking is used to hide relatively insignificant portions of feature representations from view where they conflict with other map information and make the map difficult to read or interpret. Polygons in a feature class are used to mask or cover the portions of a feature representation that you would like to hide from the view.
Once a masking relationship has been established between a feature class representation in your map and a polygon feature class, you can remove portions of feature representations from view by drawing masks. Unlike layer masking, the masks you draw will affect only the specified feature representation. Other representations in the same feature class representation will not be affected.
Masking feature representations interactively
You can interactively create masks on selected feature representations using the Mask tool on the Representation toolbar. This will add polygons to the masking polygon feature class that is linked to the feature representation.
How to mask feature representations interactively
- In an edit session, select a feature representation that belongs to a feature class representation that has a masking relationship activated.
- Select the Mask tool from the Representation toolbar.
- Click and drag over the portion of the selected feature representation that you want to mask from view. This gesture will create a polygon feature within the masking feature class.
- The mask feature class does not need to be present as a layer in the map to make masks; however, you may want add this feature class to the map temporarily to see or modify the masking polygons.
- With the Mask tool active, right-click and click Options to toggle between a round and square mask and to change its size. You can also toggle between a round and square mask by pressing the TAB key. You can interactively change the size of the mask by holding down the SHIFT key while clicking and dragging.
- Press the K key to activate the Mask tool .
Making masks from existing polygon features
You can also assign existing polygons to mask specific feature representations by linking them together with the Attribute window. The polygon and the feature representation must belong to two feature classes that have a many-to-many relationship class linking them together, and the masking relationship must be activated.
How to make masks from existing polygons
- In an edit session, use the Edit tool on the Editor toolbar to simultaneously select both the feature representation to be masked and the masking polygon.
- Open the Attribute window by clicking the Attributes button on the Editor toolbar.
- Expand the masking polygon layer by clicking the Expand button .
- Find the entry in the tree that corresponds to the selected feature representation, right-click it, then click Add Selected. This will link the two features via their relationship class and mask the feature representation with the polygon.
- Remove or turn off the mask layer in the table of contents to see the result.
The masking polygon and the feature representation must belong to two feature classes that have a many-to-many relationship class linking them together, and the masking relationship must be activated.