Function Description

Protective decomposition breaks down complex polygon objects with multi-level island-hole nested relationships into polygon objects with only a single level of island-hole nesting. The difference between protective decomposition and regular decomposition is: if the polygon object being decomposed has island-hole relationships, the result of protective decomposition will retain the simplest level of island-hole polygon objects, whereas regular decomposition will break down all island-hole polygon objects together.

• The protective decomposition function is applicable to line layers, polygon layers, and CAD layers.
• It can only decompose complex objects or compounds; simple objects cannot be decomposed.
• Decomposing a complex object (i.e., an object containing multiple sub-objects) generates multiple single objects, all of which are simple objects (except for island-hole objects). Decomposing a compound generates multiple single objects; except for island-hole objects, if any of the generated single objects are still compounds, they can be further decomposed until all objects are simple.

  As shown in the figure below, an island-hole object combined with another object is subjected to protective decomposition, resulting in a new island-hole object and a single object:

  Figure: Protective Decomposition of a Complex Object

• In the attributes of the newly generated objects, the field SmUserID and non-system fields inherit the corresponding information from the source object; other system fields are assigned by the system.

Function Entry

• Features Tab -> Feature Editing Group -> Protective Decomposition.
• Image Mosaic Tab -> Feature Editing Group -> Protective Decomposition.

Operation Steps

1. With the layer editable, select one or more complex objects or compounds.
2. In the Gallery control of the Feature Editing group on the Features tab, click the Protective Decomposition button to perform the protective decomposition operation.