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。
大纲
geometry ST_3DClosestPoint(geometry g1, geometry g2);
描述
返回 g1 上最接近 g2 的 3 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。
该函数支持 3d 并且不会丢失 z-index。
该函数支持多面体曲面。
可用性: 2.0.0
更改：2.2.0 - 如果输入 2 个 2D 几何图形，则返回 2D 点（而不是假设缺失 Z 为 0 的旧行为）。 在 2D 和 3D 情况下，对于缺失的 Z，Z 不再被假定为 0。
示例
Compare the 3D closest point to the 2D closest point for a LineString and a Point.
Code
WITH input AS (
SELECT 'POINT(100 100 30)'::geometry AS pt,
'LINESTRING (20 80 20,98 190 1,110 180 3,50 75 1000)'::geometry AS line
)
SELECT ST_3DClosestPoint(line, pt) AS cp3d_line_pt,
ST_ClosestPoint(line, pt) AS cp2d_line_pt
FROM input;
Figure
Compare the 3D closest point to the 2D closest point for a LineString and a MultiPoint.
Code
WITH input AS (
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
)
SELECT ST_3DClosestPoint(line, pt) AS cp3d_line_pt,
ST_ClosestPoint(line, pt) AS cp2d_line_pt
FROM input;
Figure
Compare the 3D closest point to the 2D closest point for a Polygon and a MultiLineString.
Code
WITH input AS (
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
)
SELECT ST_3DClosestPoint(poly, mline) AS cp3d,
ST_ClosestPoint(poly, mline) AS cp2d
FROM input;
Figure