ST_3DClosestPoint

ST_3DClosestPoint
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Name

ST_3DClosestPoint — 返回G1上最接近G2的三维点。这是3D最短直线的第一个点。

Synopsis

geometry ST_3DClosestPoint ( geometry g1 , geometry g2 ) ;

描述

返回G1上最接近G2的三维点。这是3D最短直线的第一个点。3D最短直线的3D长度是3D距离。

This function supports 3d and will not drop the z-index.

This function supports Polyhedral surfaces.

可用性：2.0.0

已更改：2.2.0-如果输入2个2D几何图形，则返回2D点(而不是假设缺少Z的行为为0)。在2D和3D的情况下，对于缺失的Z，不再假定Z为0。

示例

线串和点--三维和二维最近点

SELECT ST_AsEWKT(ST_3DClosestPoint(line,pt)) AS cp3d_line_pt,
                ST_AsEWKT(ST_ClosestPoint(line,pt)) As cp2d_line_pt
        FROM (SELECT 'POINT(100 100 30)'::geometry As pt,
                        'LINESTRING (20 80 20, 98 190 1, 110 180 3, 50 75 1000)'::geometry As line
                ) As foo;


 cp3d_line_pt                                                |               cp2d_line_pt
-----------------------------------------------------------+------------------------------------------
 POINT(54.6993798867619 128.935022917228 11.5475869506606) | POINT(73.0769230769231 115.384615384615)

线串和多点--三维和二维最近点

SELECT ST_AsEWKT(ST_3DClosestPoint(line,pt)) AS cp3d_line_pt,
                ST_AsEWKT(ST_ClosestPoint(line,pt)) As cp2d_line_pt
        FROM (SELECT 'MULTIPOINT(100 100 30, 50 74 1000)'::geometry As pt,
                        'LINESTRING (20 80 20, 98 190 1, 110 180 3, 50 75 900)'::geometry As line
                ) As foo;


                       cp3d_line_pt                        | cp2d_line_pt
-----------------------------------------------------------+--------------
 POINT(54.6993798867619 128.935022917228 11.5475869506606) | POINT(50 75)

三维和二维最近点的多线串和多边形

SELECT ST_AsEWKT(ST_3DClosestPoint(poly, mline)) As cp3d,
    ST_AsEWKT(ST_ClosestPoint(poly, mline)) As cp2d
        FROM (SELECT  ST_GeomFromEWKT('POLYGON((175 150 5, 20 40 5, 35 45 5, 50 60 5, 100 100 5, 175 150 5))') As poly,
                ST_GeomFromEWKT('MULTILINESTRING((175 155 2, 20 40 20, 50 60 -2, 125 100 1, 175 155 1),
                (1 10 2, 5 20 1))') As mline ) As foo;
                   cp3d                    |     cp2d
-------------------------------------------+--------------
 POINT(39.993580415989 54.1889925532825 5) | POINT(20 40)

另请参阅

ST_AsEWKT , ST_ClosestPoint , ST_3DDistance , ST_3DShortestLine