ST_LengthSpheroid — 返回椭球体上经度/纬度几何图形的二维或三维长度/周长。
float ST_LengthSpheroid(
geometry a_geometry, spheroid a_spheroid)
;
计算椭球体上几何图形的长度或周长。如果几何图形的坐标位于经度/纬度,并且需要长度而不需要重新投影,则此选项非常有用。椭球体由文本值指定,如下所示:
椭球体[ <NAME> , <SEMI-MAJOR AXIS> , <INVERSE FLATTENING> ]
例如:
SPHEROID["GRS_1980",6378137,298.257222101]
可用性:1.2.2
已更改:2.2.0在以前的版本中,该名称称为ST_LENGTH_ESPOIDID,别名为ST_3DLength_ESPOIDID
This function supports 3d and will not drop the z-index.
SELECT ST_LengthSpheroid( geometry_column, 'SPHEROID["GRS_1980",6378137,298.257222101]' ) FROM geometry_table; SELECT ST_LengthSpheroid( geom, sph_m ) As tot_len, ST_LengthSpheroid(ST_GeometryN(geom,1), sph_m) As len_line1, ST_LengthSpheroid(ST_GeometryN(geom,2), sph_m) As len_line2 FROM (SELECT ST_GeomFromText('MULTILINESTRING((-118.584 38.374,-118.583 38.5), (-71.05957 42.3589 , -71.061 43))') As geom, CAST('SPHEROID["GRS_1980",6378137,298.257222101]' As spheroid) As sph_m) as foo; tot_len | len_line1 | len_line2 ------------------+------------------+------------------ 85204.5207562955 | 13986.8725229309 | 71217.6482333646 --3D SELECT ST_LengthSpheroid( geom, sph_m ) As tot_len, ST_LengthSpheroid(ST_GeometryN(geom,1), sph_m) As len_line1, ST_LengthSpheroid(ST_GeometryN(geom,2), sph_m) As len_line2 FROM (SELECT ST_GeomFromEWKT('MULTILINESTRING((-118.584 38.374 20,-118.583 38.5 30), (-71.05957 42.3589 75, -71.061 43 90))') As geom, CAST('SPHEROID["GRS_1980",6378137,298.257222101]' As spheroid) As sph_m) as foo; tot_len | len_line1 | len_line2 ------------------+-----------------+------------------ 85204.5259107402 | 13986.876097711 | 71217.6498130292