語法

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

參數

描述

• 該函數支持3D對象，并且不會刪除Z坐標。

• 該函數支持M坐標。

• 使用地理坐標系時會根據球面距離進行計算。

示例

• 計算給定線段的中點坐標：

  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)

• 獲取線上距離某個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)