2011

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.
The geometry in the feature classes or layers you select determines the other
choices in the dialog box. You can combine only certain types of geometries.
For example, Union, Paste, and Symmetric Difference support
polygon/polygon comparisons only. Also, you cannot choose point
geometries for both Source and Overlay. If you select point geometry for
Source, you can select only polygon geometry for Overlay.
The available choices for Type depend on the geometry in the Source and
Overlay.
If either the Source or the Overlay contains multiple geometries, you can
select any feature class or layer in Overlay and any overlay operation in
Type. However, the output may be empty if there are no valid geometry
combinations.
Type
Select the type of overlay comparison to perform. For more information on
the available types, see
Overlaying Two Feature Sources (page 1309).
■ Intersect: Determines the geometry that overlaps in the Source and
Overlay features. Anything that does not overlap is discarded from the
output.
■ Union: Determines the geometry that exists in either the Source or
Overlay geometry. Where the geometry intersects, additional features
are created. The resulting layer is the sum of the two comparison layers.
■ Erase: Determines the geometry from the Source that does not intersect
with the Overlay. The intersecting pieces are discarded.
■ Identity: Creates new features where the Source and Overlay features
intersect.
■ Clip: Like Intersect, Clip creates features from the areas of the Source
that overlap with the Overlay. However, with Clip, only feature attributes
from the Source are included in the resulting layer.
■ Paste: Creates new features by pasting the Overlay features onto the
Source features. All Overlay features become new features in the resulting
layer. In addition, areas of the Source that do not fall within the geometry
of the Overlay become features in the resulting layer.
■ Symmetric Difference: Determines geometry of the Source and Overlay
that do not overlap. Overlapping areas of the features are discarded in
the output, so the resulting layer represents the areas that are mutually
exclusive.
1564 | Chapter 14 Analyzing Data Dialog Boxes