ST_ApproximateMedialAxis

Introduction: Computes an approximate medial axis of a polygonal geometry. The medial axis is a representation of the "centerline" or "skeleton" of the polygon. This function first computes the straight skeleton and then prunes insignificant branches to produce a cleaner result.

The pruning removes small branches that represent minor penetrations into corners. A branch is pruned if its penetration depth is less than 20% of the width of the corner it bisects.

This function may have significant performance limitations when processing polygons with a very large number of vertices. For very large polygons (e.g., 10,000+ vertices), applying vertex reduction or simplification is essential to achieve practical computation times.

Format: ST_ApproximateMedialAxis(geom: geometry)

SQL example:

SELECT Sedona.ST_ApproximateMedialAxis(
  ST_GeometryFromWKT('POLYGON ((45 0, 55 0, 55 40, 70 40, 70 50, 30 50, 30 40, 45 40, 45 0))')
)

Output: MULTILINESTRING ((50 45, 50 5), (50 45, 35 45), (65 45, 50 45), (35 45, 65 45))