DonutHoleExtractor

Separates donut polygons into outer shell and hole polygons.

Typical Uses

Creating geometry for holes
Filling in holes to create non-donut areas

How does it work?

The DonutHoleExtractor receives features with donut area geometry and separates the holes from the outer shell of the polygon, creating individual geometry for each hole.

Features are output as either Outershell or Hole. All output features have non-donut area geometry.

In the case of nested donuts - such as a lake on an island in a lake - holes that contain a smaller hole are output twice, via both the Outershell and Hole output ports.

Aggregates may be either deaggregated or rejected.

Features with invalid or non-area geometry are rejected.

Examples

Usage Notes

Creating and Modifying Area Features

These transformers work with polygons in a variety of ways.

Area Transformers Comparison

Transformer	Use this to...	Transformer Description
Creator	Create one or more new features with area geometry (when Geometry Object is Polygon).	Creates features using the parameters supplied, and sends them into the workspace for processing.
AreaBuilder	Create areas from topologically connected lines where they form closed shapes.	Creates polygons from topologically correct linear features.
LineCloser	Create areas from individual linear features.	Converts a linear feature to an area by connecting the end point to the start point.
Dissolver	Combine touching or overlapping areas to create larger areas.	Combines overlapping and/or adjacent areas into larger contiguous areas by removing shared and interior edges.
AreaCalculator	Calculate areas.	Calculates the planar or sloped area of polygon geometries and adds the results as attributes.
AreaGapAndOverlapCleaner	Clean up overlaps and gaps to create contiguous coverage.	Repairs area topologies by resolving gaps and overlaps between adjacent areas.
AreaAmalgamator	Generalize areas.	Generalizes area geometry by connecting and combining neighboring features and/or filling in holes and details.
DonutBridgeBuilder	Convert donut areas to non-donut areas.	Adds internal edges to connect donut holes to the outer shell, producing a non-donut polygon.
DonutBuilder	Convert areas within areas to donut holes.	Cuts holes in area features where they fully enclose another area, creating donut polygons.
DonutHoleExtractor	Separate donut areas into their parts.	Separates donut polygons into outer shell and hole polygons.
HoleCounter	Count the number of holes in a donut area.	Retrieves the number of holes in donut polygons, storing the result as an attribute.
AreaOnAreaOverlayer	Find polygon overlaps and extract them into new geometry.	Performs an area-on-area overlay (intersection of polygons) so that all input areas are intersected against each other and resultant area features are created and output. The resultant areas can accumulate attribute from any overlapping polygons.
LineOnAreaOverlayer	Find intersections between lines and polygons, splitting either where they intersect.	Performs a line-on-area overlay, either splitting lines where they intersect area boundaries or subdividing areas where split by lines. Attributes may be shared between related lines and areas (spatial join).
PointOnAreaOverlayer	Identify points that fall within polygons, and share attributes between them.	Performs a point-in-polygon overlay. Points may receive containing area attributes, and areas may receive contained point attributes (spatial join).

Configuration

Input Ports

Output Ports

Parameters

Editing Transformer Parameters

Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click beside the applicable parameter.

How to Set Parameter Values

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters.

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

Content Types

String Functions	These functions manipulate and format strings.
Special Characters	A set of control characters is available in the Text Editor.
Math Functions	Math functions are available in both editors.
Date/Time Functions	Date and time functions are available in the Text Editor.
Math Operators	These operators are available in the Arithmetic Editor.
FME Feature Functions	These return primarily feature-specific values.
FME Parameters	FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters	Create your own editable parameters.

Dialog Options - Tables

Table Tools

Transformers with table-style parameters have additional tools for populating and manipulating values.

Row Reordering

Enabled once you have clicked on a row item. Choices include:

Add a row
Remove a row
Move current row up one
Move current row down one
Move current row to top
Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

Cut a row - delete and copy to clipboard
Copy a row to the clipboard
Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

For more information, see Transformer Parameter Menu Options.

Reference

Processing Behavior	Feature-Based
Feature Holding	No
Dependencies	None
Aliases
History

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Examples may contain information licensed under the Open Government Licence – Vancouver, Open Government Licence - British Columbia, and/or Open Government Licence – Canada.