Description of the Spinalize Algorithm

Description of the algorithm

The spinalize algorithm collapses a polygon into a line based on a voronoï diagram of the polygon, keeping only the “spine” of the skeleton (the algorithm gets rid of the small edges of the skeleton). If several polygons are initially connected (i.e. they touch each other) their spine is also connected by the algorithm.

A river area that is densified in vertices, and decomposed into a Voronoï diagram

The algorithm is briefly described in two papers that can be found here and here.

Parameter name Description Type Default value
lengthMin minimum length to keep a segment in the spine of the skeleton double (meters)  
overSample a step for the vertex oversampling performed before computing the Voronoï diagram double (meters)  
removeHoles true if you want to remove holes prior to collapse boolean true

Examples of generalization

A river area spinalized

When to use the algorithm?

The algorithm can be used to collapse thin areas into lines (e.g. rivers, hedges, taxiways). When the shapes of the areas are not very thin, or are very complex, the algorithm provides not very smooth lines, and a straight skeleton based collapse should be preferred.

See Also