描述

使用Douglas-Peucker算法返回给定几何体的简化版本。将避免创建无效的衍生几何图形(特别是多边形)。我实际上只对(多)线和(多)多边形做了一些事情，但你可以安全地用任何类型的几何体调用它。由于简化是在逐个对象的基础上进行的，因此您还可以将GeometryCollection提供给此函数。

由GEOS模块执行。

可用性：1.3.3

示例

与简化相同的示例，但我们看到保留拓扑可防止过度简化。这个圆最多只能变成一个正方形。

SELECT ST_Npoints(geom) As np_before, ST_NPoints(ST_SimplifyPreserveTopology(geom,0.1)) As np01_notbadcircle, ST_NPoints(ST_SimplifyPreserveTopology(geom,0.5)) As np05_notquitecircle,
ST_NPoints(ST_SimplifyPreserveTopology(geom,1)) As np1_octagon, ST_NPoints(ST_SimplifyPreserveTopology(geom,10)) As np10_square,
ST_NPoints(ST_SimplifyPreserveTopology(geom,100)) As  np100_stillsquare
FROM (SELECT ST_Buffer('POINT(1 3)', 10,12) As geom) As foo;

--result--
 np_before | np01_notbadcircle | np05_notquitecircle | np1_octagon | np10_square | np100_stillsquare
-----------+-------------------+---------------------+-------------+---------------+-------------------
        49 |                33 |                  17 |           9 |             5 |                 5
                

另请参阅

ST_Simplify