Name
ST_Polygonize — 计算由一组几何图形的线条形成的多边形集合。
Synopsis
geometry
ST_Polygonize
(
geometry set
geomfield
)
;
geometry
ST_Polygonize
(
geometry[]
geom_array
)
;
描述
创建包含由一组几何图形的组成线条形成的多边形的GeometryCollection。必须正确标记输入线条，此功能才能正常工作。
![[Note]](images/note.png)
|
|
|
要确保输入是完全节点的，请使用 ST_Node 在多边形化之前的输入几何体上。 |
|
|
|
|
GeometryCollection通常很难用第三方工具来处理。使用 ST_Dump 若要将多边形化结果转化为单独的多边形，请执行以下操作。 |
由GEOS模块执行。
可用性：1.0.0RC1
示例：多边形化单线串
SELECT ST_AsEWKT(ST_Polygonize(geom_4269)) As geomtextrep
FROM (SELECT geom_4269 FROM ma.suffolk_edges ORDER BY tlid LIMIT 45) As foo;
geomtextrep
-------------------------------------
SRID=4269;GEOMETRYCOLLECTION(POLYGON((-71.040878 42.285678,-71.040943 42.2856,-71.04096 42.285752,-71.040878 42.285678)),
POLYGON((-71.17166 42.353675,-71.172026 42.354044,-71.17239 42.354358,-71.171794 42.354971,-71.170511 42.354855,
-71.17112 42.354238,-71.17166 42.353675)))
(1 row)
--Use ST_Dump to dump out the polygonize geoms into individual polygons
SELECT ST_AsEWKT((ST_Dump(foofoo.polycoll)).geom) As geomtextrep
FROM (SELECT ST_Polygonize(geom_4269) As polycoll
FROM (SELECT geom_4269 FROM ma.suffolk_edges
ORDER BY tlid LIMIT 45) As foo) As foofoo;
geomtextrep
------------------------
SRID=4269;POLYGON((-71.040878 42.285678,-71.040943 42.2856,-71.04096 42.285752,
-71.040878 42.285678))
SRID=4269;POLYGON((-71.17166 42.353675,-71.172026 42.354044,-71.17239 42.354358
,-71.171794 42.354971,-71.170511 42.354855,-71.17112 42.354238,-71.17166 42.353675))
(2 rows)