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
创建一个 GeometryCollection，其中包含由一组几何图形的线条形成的多边形。 如果输入线条未形成任何多边形，则返回空的 GeometryCollection。
此函数创建覆盖所有分隔区域的多边形。 如果结果旨在形成有效的多边形几何体，请使用 ST_BuildArea 来防止填充孔。
![[Note]](../images/note.png)
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输入线条必须正确节点才能使该功能正常工作。 为了确保输入已节点化，请在多边形化之前在输入几何体上使用 ST_Node。 |
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使用外部工具可能很难处理几何集合。 使用ST_Dump 将多边形结果转换为单独的多边形。 |
这个函数是由 GEOS 模块执行的。
可用性： 1.0.0RC1
示例
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输入线
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多边形化结果
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WITH data(geom) AS (VALUES
('LINESTRING (180 40, 30 20, 20 90)'::geometry)
,('LINESTRING (180 40, 160 160)'::geometry)
,('LINESTRING (80 60, 120 130, 150 80)'::geometry)
,('LINESTRING (80 60, 150 80)'::geometry)
,('LINESTRING (20 90, 70 70, 80 130)'::geometry)
,('LINESTRING (80 130, 160 160)'::geometry)
,('LINESTRING (20 90, 20 160, 70 190)'::geometry)
,('LINESTRING (70 190, 80 130)'::geometry)
,('LINESTRING (70 190, 160 160)'::geometry)
)
SELECT ST_AsText( ST_Polygonize( geom ))
FROM data;
------------------------------------------------------------------------------------------
GEOMETRYCOLLECTION (POLYGON ((180 40, 30 20, 20 90, 70 70, 80 130, 160 160, 180 40), (150 80, 120 130, 80 60, 150 80)),
POLYGON ((20 90, 20 160, 70 190, 80 130, 70 70, 20 90)),
POLYGON ((160 160, 80 130, 70 190, 160 160)),
POLYGON ((80 60, 120 130, 150 80, 80 60)))
多边形线串表：
SELECT ST_AsEWKT(ST_Polygonize(geom_4269)) As geomtextrep
FROM (SELECT geom_4269 FROM ma.suffolk_edges) As foo;
-------------------------------------
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)))
--Use ST_Dump to dump out the polygonize geoms into individual polygons
SELECT ST_AsEWKT((ST_Dump(t.polycoll)).geom) AS geomtextrep
FROM (SELECT ST_Polygonize(geom_4269) AS polycoll
FROM (SELECT geom_4269 FROM ma.suffolk_edges)
As foo) AS t;
------------------------
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))