DonutBridgeBuilder
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Description
This transformer forms connections between donut holes with the outer boundary of a donut, resulting in a polygon-equivalent representation of the input donut. A single, connected path visits the boundary and each donut hole exactly once. This boundary is guaranteed to be non-self-intersecting.
If the input is not a donut, the geometry will not be processed.
Example
The attached archive contains two workspaces showing use of the DonutBridgeBuilder transformer.
The DonutBridgeBuilder transformer builds a route of bridges that cross over the holes or islands of a donut, so that whatever or whoever follows the route can visit each feature only once (backtracks excepted) and without crossing over his own track. This also results in a non-donut feature that is equivalent in outline to the original feature.
The DonutBridgeSimple.fmw workspace uses a donut with regularly placed holes that allow to see easily how it works:
The second workspace DonutBridgeSanJuan.fmw takes a county in Washington, USA, consisting of several islands, cuts them from an expanded bounding box, and converts the remaining donut into a polygon:
