ST_LengthSpheroid
Prev | 8.12. Measurement Functions | Next

## Name

ST_LengthSpheroid — Returns the 2D or 3D length/perimeter of a lon/lat geometry on a spheroid.

## Synopsis

`float ST_LengthSpheroid(`geometry a_geometry, spheroid a_spheroid`)`;

## Description

Calculates the length or perimeter of a geometry on an ellipsoid. This is useful if the coordinates of the geometry are in longitude/latitude and a length is desired without reprojection. The spheroid is specified by a text value as follows:

SPHEROID[<NAME>,<SEMI-MAJOR AXIS>,<INVERSE FLATTENING>]

For example:

SPHEROID["GRS_1980",6378137,298.257222101]

Availability: 1.2.2

Changed: 2.2.0 In prior versions this was called ST_Length_Spheroid and had the alias ST_3DLength_Spheroid

This function supports 3d and will not drop the z-index.

## Examples

    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

## See Also

ST_GeometryN, ST_Length

Prev | Up | Next
ST_3DLength | Home | ST_LongestLine