Name
ST_VoronoiPolygons — Returns the cells of the Voronoi diagram of the vertices of a geometry.
Synopsis
geometry ST_VoronoiPolygons( geometry geom , float8 tolerance = 0.0 , geometry extend_to = NULL );
설명
Computes a two-dimensional Voronoi diagram from the vertices of the supplied geometry. The result is a GEOMETRYCOLLECTION of POLYGONs that covers an envelope larger than the extent of the input vertices. Returns null if input geometry is null. Returns an empty geometry collection if the input geometry contains only one vertex. Returns an empty geometry collection if the extend_to envelope has zero area.
선택할 수 있는 파라미터:
-
tolerance: The distance within which vertices will be considered equivalent. Robustness of the algorithm can be improved by supplying a nonzero tolerance distance. (default = 0.0) -
extend_to: If present, the diagram is extended to cover the envelope of the supplied geometry, unless smaller than the default envelope (default = NULL, default envelope is the bounding box of the input expanded by about 50%).
GEOS 모듈로 실행
2.3.0 버전부터 사용할 수 있습니다.
예시
Points overlaid on top of Voronoi diagram
SELECT ST_AsText(ST_VoronoiPolygons('MULTIPOINT (50 30, 60 30, 100 100,10 150, 110 120)'::geometry
)) AS geom;
GEOMETRYCOLLECTION(POLYGON((-110 270,100.5 270,59.34782608695652 132.82608695652175,36.81818181818182 92.27272727272727,-110 43.33333333333332,-110 270)), POLYGON((-110 -90,-110 43.33333333333332,36.81818181818182 92.27272727272727,55 79.28571428571429,55 -90,-110 -90)), POLYGON((230 -20.71428571428572,55 79.28571428571429,36.81818181818182 92.27272727272727,59.34782608695652 132.82608695652175,230 47.50000000000001,230 -20.71428571428572)),POLYGON((230 -90,55 -90,55 79.28571428571429,230 -20.71428571428572,230 -90)), POLYGON((230 270,230 47.50000000000001,59.34782608695652 132.82608695652175,100.5 270,230 270)))
Voronoi diagram, with tolerance of 30 units
SELECT ST_AsText(ST_VoronoiPolygons('MULTIPOINT (50 30, 60 30, 100 100,10 150, 110 120)'::geometry,
30)) AS geom;
GEOMETRYCOLLECTION(POLYGON((-110 270,135.55555555555557 270,36.81818181818182 92.27272727272727,-110 43.33333333333332,-110 270)), POLYGON((230 270,230 -45.71428571428574,36.81818181818182 92.27272727272727,135.55555555555557 270,230 270)), POLYGON((230 -90,-110 -90,-110 43.33333333333332,36.81818181818182 92.27272727272727,230 -45.71428571428574,230 -90)))