Name
ST_NDims — 返回几何体的坐标维度。
Synopsis
integer ST_NDims(geometry g1);
描述
返回几何体的坐标维度。PostGIS 支持 2 - (x,y) 、3 - (x,y,z) 或 2D 测量 - x,y,m 和 4 - 3D 测量空间 x,y,z,m
该函数支持 3d 并且不会丢失 z-index。
示例
SELECT ST_NDims(ST_GeomFromText('POINT(1 1)')) As d2point,
ST_NDims(ST_GeomFromEWKT('POINT(1 1 2)')) As d3point,
ST_NDims(ST_GeomFromEWKT('POINTM(1 1 0.5)')) As d2pointm;
d2point | d3point | d2pointm
---------+---------+----------
2 | 3 | 3