ST_LineInterpolatePoint - ApsaraDB RDS

在LineString上指定位置插入點對象，並返回該點。

文法

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

參數

參數名稱	描述
aLinestring	目標LineString對象。
aFraction	插入點位於該線段的百分比，是一個從0到1的浮點值。

描述

該函數支援3D對象，並且不會刪除Z座標。
該函數支援M座標。
使用地理座標系時會根據球面距離進行計算。

樣本

計算給定線段的中點座標：

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)

擷取線上距離某個Geometry對象最近的點：

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)