ST_LineToCurve
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Name

ST_LineToCurve — 将线性几何图形转换为曲线几何图形。

Synopsis

geometry ST_LineToCurve(geometry geomANoncircular);

描述

将普通线/多边形转换为圆形线和曲线多边形。 请注意，描述等效曲线所需的点要少得多。

[Note]

如果输入线串/多边形不足以清楚地表示曲线，则该函数返回与输入几何图形相同的值。

可用性：1.3.0

该函数支持 3d 并且不会丢失 z-index。

此方法支持圆形字符串和曲线。

示例

This example uses 2D input.

SELECT ST_AsText(ST_LineToCurve(foo.geom)) As curvedastext,ST_AsText(foo.geom) As non_curvedastext
    FROM (SELECT ST_Buffer('POINT(1 3)'::geometry, 3) As geom) As foo;

curvedatext                                                            non_curvedastext
--------------------------------------------------------------------|-----------------------------------------------------------------
CURVEPOLYGON(CIRCULARSTRING(4 3,3.12132034355964 0.878679656440359, | POLYGON((4 3,3.94235584120969 2.41472903395162,3.77163859753386 1.85194970290473,
1 0,-1.12132034355965 5.12132034355963,4 3))                        |  3.49440883690764 1.33328930094119,3.12132034355964 0.878679656440359,
                                                                    |  2.66671069905881 0.505591163092366,2.14805029709527 0.228361402466141,
                                                                    |  1.58527096604839 0.0576441587903094,1 0,
                                                                    |  0.414729033951621 0.0576441587903077,-0.148050297095264 0.228361402466137,
                                                                    |  -0.666710699058802 0.505591163092361,-1.12132034355964 0.878679656440353,
                                                                    |  -1.49440883690763 1.33328930094119,-1.77163859753386 1.85194970290472
                                                                    |  --ETC-- ,3.94235584120969 3.58527096604839,4 3))

This example uses 3D input.

SELECT ST_AsText(ST_LineToCurve(geom)) As curved, ST_AsText(geom) AS not_curved
FROM (SELECT ST_Translate(ST_Force3D(ST_Boundary(ST_Buffer(ST_Point(1,3), 2,2))),0,0,3) AS geom) AS foo;
curved                                      | not_curved
--------------------------------------------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
CIRCULARSTRING Z (3 3 3,-1 3 3,3 3 3)      | LINESTRING Z (3 3 3,2.414213562373095 1.585786437626905 3,1 1 3,-0.414213562373095 1.585786437626905 3,-1 3 3,-0.414213562373095 4.414213562373095 3,1 5 3,2.414213562373095 4.414213562373096 3,3 3 3)
(1 row)

相关信息

ST_CurveToLine