使用ST_LineInterpolatePoint进行线性参考_云原生数据库 PolarDB(PolarDB)-阿里云帮助中心

在LineString上指定位置插入点对象，并返回该点。

语法

geometry  ST_LineInterpolatePoint(geometry  aLinestring , float8  aFraction);
geography  ST_LineInterpolatePoint(geography  aLinestring , float8  aFraction);

参数

参数名称	描述
aLinestring	目标LineString对象。
aFraction	插入点位于该线段的百分比，是一个从0到1的浮点值。

描述

该函数支持3D对象，并且不会删除Z坐标。
该函数支持M坐标。
使用地理坐标系时会根据球面距离进行计算。

示例

计算给定线段的中点坐标：

SELECT ST_AsText(ST_LineInterpolatePoint(geom, 0.5)) FROM (SELECT 'LINESTRING(0 0,2 2)'::geometry as geom) As test;
 st_astext
------------
 POINT(1 1)
(1 row)


SELECT ST_AsText(ST_LineInterpolatePoint(geog, 0.5)) FROM (SELECT 'LINESTRING(0 0,2 2)'::geography as geog) As test;

------------------------------------------
 POINT(0.99969732796684 1.00015638159834)

获取线上距离某个Geometry对象最近的点：

SELECT ST_AsText(ST_LineInterpolatePoint(geom, ST_LineLocatePoint(geom, 'POINT(1 1)'::geometry))) FROM (SELECT 'LINESTRING(0 0,0 2)'::geometry As geom) As test;
 st_astext
------------
 POINT(0 1)
(1 row)

-- geography
SELECT ST_AsText(ST_LineInterpolatePoint(geog, ST_LineLocatePoint(geog, 'POINT(1 1)'::geography))) FROM (SELECT 'LINESTRING(0 0,0 2)'::geography As geog) As test;
---------------------------
 POINT(0 1.00015229710421)