Operations of intersection and interception of features are applicable to area and image features.
Intersection of two features (or feature and a polygon) is building of a set of points belonging to both features.
Interception of one feature by another one (or by a polygon) is building a set of points belonging to the first feature, but not belonging to the second one.
If two features do not have common points, their intersection is impossible, however, interception can be performed (in this case the feature is just not changed).
As a result of the operation of intersection or interception, one or several new features can be formed.
To perform the operation of intersection it is necessary to switch to the mode Edit and select an area or image feature for editing. Then one should call the context menu by right-clicking, select the menu item Intersect and operation variant With Feature or With Polygon.
On analogy, for performing the operation of interception it is required to select an area or image feature for editing and perform the context menu item Intercept+By Feature or Intercept+By Polygon.
If the variant By Feature is selected, the user should select the text or image feature engaged in the operation clicking on it.
If the variant By Polygon is selected, the user should add a polygon used for intersection or interception clicking on it.
Before the operation is performed a dialog box “Intersection of feature” or a dialog box “Interception of feature” is displayed which is analogous to the dialog box “Combining features” at figure 18-1. The dialog box shows the status of the operation “The operation is possible” or “Cannot perform the operation”. The reason for impossibility of performing the operation can be incorrectness of the built polygon, and for operation of intersection – also absence of the common area with the source feature.
If the box Remove intersected features is checked for the operation of intersection, after it is performed the source feature will be removed (if intersection with a feature was performed both features will be removed). Similarly, if the box Remove intercepted feature is checked for the operation of interception, after it is performed, the source feature will be removed. A feature using which interception was performed is not removed.
The checkbox Save links with records when interception is performed determines if the new feature should inherit the links with table records which the source feature had or not (see chapter 32 “Links between maps and tables”). If the box is cleared the new feature will not have links with records.
At figure 18-6 results of operations of intersection and interception for area feature and polygon are shown.
Figure 18-6. Intersection and interception of a feature with a polygon
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