Feature

Feature Description

A donut polygon is a complex geometry type. In editable state, it processes overlapping areas between two or more polygon objects with containment relationships (deleting or retaining - even numbers of polygons delete overlapping areas, odd numbers retain them), ultimately forming a donut polygon. For example, when a region contains a lake, a donut polygon is generated.

• Donut polygons apply to polygon layers or CAD layers.
• When performing donut polygon operations on two or more selected polygon objects, the following scenarios occur:
  • If selected polygons do not intersect, a complex object is generated.
  • If selected polygons intersect at points or lines, they merge into a single complex object.
  • If selected polygons intersect on areas but do not overlap completely: When object count is odd, intersecting areas are retained to form a complex object; when even, intersecting areas are deleted to form a complex object.

    Retain odd count faces, remove even count faces

  • If selected polygons completely overlap: When overlap count is odd, a single polygon remains; when even, all polygons are deleted.

  Three overlapping circles produce one circle after donut polygon operation; two overlapping circles yield null.

Feature Entry

• Features Tab->Feature Editing Group->Donut Polygon.

Steps

1. Select one or more polygon objects while the layer is editable.
2. Click the Donut Polygon button in the Feature Editing group under the Features Tab to open the Donut Polygon dialog.

   The Donut Polygon dialog allows setting operation methods per field or batch configuring multiple fields. Dialog components:

   • Edit Layer: The dropdown lists all editable layers in the current map. Select target layer via the arrow.
   • Field List Area: Displays all non-system fields and editable system fields in the current layer, including field name, type, and post-operation handling. Default uses first object's field attributes.
   • Operation Method Settings: Four operation types:
     • Null: New object's field value becomes null.
     • Sum: New object's field value equals sum of source objects' corresponding fields.
     • Weighted Mean: New object's field value equals weighted average of source fields. Requires specifying a weight field. Without selection, calculates simple average (sum divided by object count).
     • Save Geometry: New object's field value matches a selected object's property. Use dropdown to select source.
   • Keep Hole: When checked, preserves the hole area from donut polygon operation as a separate polygon object for further operations and styling. Unchecked (left image) leaves hole area blank; checked (right image) creates a hole polygon:

     Figure: Donut Polygon Result Comparison

3. Click OK to complete the operation.