Function Description

Protective decomposition is used to decompose complex objects or compounds. After performing protective decomposition on a polygon object with multi-level island-hole nesting relationships, it can be decomposed into polygon objects with only one level of island-hole nesting relationship.

The difference between protective decomposition and decomposition is: if the polygon object to be decomposed has an island-hole relationship, the result after protective decomposition will retain the polygon objects with the simplest level of island-hole relationships, while decomposition will decompose all polygon objects with island-hole relationships together.

The following limitations should be noted when using this function:

• Line layers do not support protective decomposition, regardless of whether the selected object is a compound or a complex object.
• Polygon layers support performing protective decomposition on compounds and complex objects.
• In CAD layers, the support for polygon objects is the same as for ordinary polygon layers; among line objects, only compound line objects support protective decomposition, while complex line objects do not.
• Simple objects cannot be decomposed.
• In the supported object scope, decomposing a complex object (i.e., an object containing multiple sub-objects) generates multiple single objects that are all simple objects (except for island-hole objects); decomposing a compound generates multiple single objects. Except for island-hole objects, if any resulting single object is still a compound, it can be further decomposed until all are simple objects.

  As shown in the figure below, an island-hole object is combined with another object. After performing the protective decomposition operation on it, the resulting new objects are one island-hole object and one single object:

  Figure: Protective decomposition of a complex object

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

Function Entry

• Edit Data tab -> Object Editing group -> General editing -> Group and Ungroup -> protective decomposition。

Operation Steps

1. In the editable state of a layer that supports protective decomposition, select one or more decomposable objects.
2. In the Edit Data tab's Object Editing group, click the General editing drop-down menu, and in the Group and Ungroup group, click the Protective Decomposition button to perform the protective decomposition operation.