名称
ST_3DClosestPoint — 返回 g1 上最接近 g2 的 3D 点。这是 3D 最短线的第一个点。
语法
geometry ST_3DClosestPoint(geometry g1, geometry g2);
说明
返回 g1 上最接近 g2 的三维点。这是 3D 最短线的第一个点。3D 最短线的 3D 长度是 3D 距离。
此函数支持 3d，并且不会丢弃 z 索引。
此函数支持多面体表面。
可用性：2.0.0
更改：2.2.0 - 如果输入 2 个 2D 几何，则返回一个 2D 点（而不是旧行为，即假设缺失 Z 为 0）。如果为 2D 和 3D，则不再假设缺失 Z 为 0。
示例
线串和点 -- 3d 和 2d 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)
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线串和多点 -- 3d 和 2d 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)
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多线串和多边形 3d 和 2d 最近点 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)
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