Name
ST_LengthSpheroid — 返回椭球体上经度/纬度几何体的 2D 或 3D 长度/周长。
Synopsis
float ST_LengthSpheroid(geometry a_geometry, spheroid a_spheroid);
描述
返回椭球体面上几何图形的周长。 当几何图形的坐标为经度/纬度并且您希望查找没有投影的长度时，请使用此函数。椭球体由文本值指定，如下所示：
SPHEROID[<NAME
>,<SEMI-MAJOR AXIS
>,<INVERSE FLATTENING
>]
例如：
SPHEROID["GRS_1980",6378137,298.257222101]
可用性：1.2.2
更改：2.2.0 在之前的版本中，这称为 ST_Length_Spheroid 并具有别名 ST_3DLength_Spheroid
该函数支持 3d 并且不会丢失 z-index。
示例
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