Name
ST_Perimeter — Return the length measurement of the boundary of an ST_Surface or ST_MultiSurface value. (Polygon, Multipolygon)
Synopsis
float ST_Perimeter(geometry g1);
Description
Returns the 2D perimeter of the geometry if it is a ST_Surface, ST_MultiSurface (Polygon, Multipolygon). 0 is returned for non-areal geometries. For linestrings use ST_Length. Measurements are in the units of the spatial reference system of the geometry.
Currently this is an alias for ST_Perimeter2D, but this may change to support higher dimensions.
This method implements the OpenGIS Simple Features
Implementation Specification for SQL. OGC SPEC 2.1.5.1
This method implements the SQL/MM specification:
SQL-MM 3: 8.1.3, 9.5.4
Examples
Return perimeter in feet for polygon and multipolygon. Note this is in feet because 2249 is Mass State Plane Feet
SELECT ST_Perimeter(ST_GeomFromText('POLYGON((743238 2967416,743238 2967450,743265 2967450,
743265.625 2967416,743238 2967416))', 2249));
st_perimeter
---------
122.630744000095
(1 row)
SELECT ST_Perimeter(ST_GeomFromText('MULTIPOLYGON(((763104.471273676 2949418.44119003,
763104.477769673 2949418.42538203,
763104.189609677 2949418.22343004,763104.471273676 2949418.44119003)),
((763104.471273676 2949418.44119003,763095.804579742 2949436.33850239,
763086.132105649 2949451.46730207,763078.452329651 2949462.11549407,
763075.354136904 2949466.17407812,763064.362142565 2949477.64291974,
763059.953961626 2949481.28983009,762994.637609571 2949532.04103014,
762990.568508415 2949535.06640477,762986.710889563 2949539.61421415,
763117.237897679 2949709.50493431,763235.236617789 2949617.95619822,
763287.718121842 2949562.20592617,763111.553321674 2949423.91664605,
763104.471273676 2949418.44119003)))', 2249));
st_perimeter
---------
845.227713366825
(1 row)