Function Description

The donut polygon is a type of complex geometry. In the editable state, it processes two or more polygon objects with containment relationships in their overlapping areas (either deleting or retaining them; if the number of polygon objects is even, the overlapping part is deleted; if odd, it is retained), ultimately forming a donut polygon. For example, if there is a lake within a region, a donut polygon is obtained.

• The donut polygon operation applies to polygon layers or CAD layers.
• Select two or more polygon objects and perform the donut polygon operation. The following situations may occur:
  • If the selected polygon objects do not intersect with each other, a complex object is generated.
  • If the selected polygon objects intersect at points or lines, these polygon objects are merged into one complex object.
  • If the selected polygon objects intersect in area but do not completely overlap, when the polygon object count is odd, the intersecting area of the polygon objects is retained, resulting in one complex object; when the polygon object count is even, the intersecting area is deleted, also resulting in one complex object.

    Retain The Overlap For Odd Count, Delete For Even Count

  • If the selected polygon objects completely coincide, when the coincidence count is odd, the result is one polygon object; when the polygon object count is even, all polygon objects are deleted.

  Performing the donut polygon operation on three coincident circles results in one circle object; performing the operation on two coincident circles results in null.

Functional Portal

• Edit Data Tab -> Feature Editing Group -> Face Editing -> Hole Treatment -> Donut Polygon

Operational Instructions

1. When the layer is in an editable state, select one or more polygon objects.
2. In the Edit Data tab, click the Donut Polygon button in the Hole Treatment group under the Face Editing dropdown menu. The Donut Polygon dialog box appears.

   In the Donut Polygon dialog box, you can set the operation mode for each field individually or select multiple fields to set them uniformly. The following explains this dialog box.

   • Edit Layer: The editable layer dropdown list shows all editable layers in the current map. Click the dropdown arrow on its right to select the layer to operate on.
   • Field List Area: This area lists information for all non-system fields and editable system fields in the current editable layer, including the field, type, and the operation mode for the field of the new object after the connection operation is complete. The field attributes of the first object are used by default.
   • Operation Mode Setting Area: Provides four operation modes:
     • Is Empty: Means the value of this field for the new object will be empty after the operation is completed.
     • Sum: Means the value of this field for the new object will be the sum of the corresponding field values from each source operation object after the operation is completed.
     • Weighted Mean: Means the value of this field for the new object will be the weighted mean of this field's values from all source objects after the operation is completed. A weighting field needs to be specified. If no weighting field is selected, the simple average is calculated, which is the sum of the selected field values of all source objects divided by the number of source objects.
     • Save Geometry: Means the value of this field for the new object will be the same as that of a currently selected object after the operation is completed. You can click the dropdown arrow on the right to select the object properties value to be used for the new object.
   • Keep Hole: Check this box to save the hole area in the donut polygon operation result as a separate polygon object, making it convenient for users to perform other operations and settings on that object. As shown in the figure below, if this box is not checked, there is no object in the hole area, which appears blank (left image); after checking the Keep Hole box, the hole area in the result is saved as a polygon object (right image), allowing users to set its style, attributes, etc.

     Figure: Donut Polygon Result Comparison

3. Click the OK button to complete the donut polygon operation.