描述

若幾何/地理為 ST_Surface、ST_MultiSurface (Polygon、MultiPolygon)，則傳回其 2D 周長。非面狀幾何則傳回 0。若為線狀幾何，請使用 ST_Length。對於幾何類型，周長測量的單位由幾何的空間參考系統指定。

對於地理類型，計算是使用逆大地測量問題執行的，周長單位為公尺。如果 PostGIS 使用 PROJ 4.8.0 或更高版本編譯，則橢球體由 SRID 指定，否則專屬於 WGS84。如果 use_spheroid = false，則計算將近似為球體，而不是橢球體。

目前這是一個 ST_Perimeter2D 的別名，但這可能會更改以支援更高的維度。

此方法實作了 OGC 簡單功能 SQL 1.1 實作規範 s2.1.5.1

此方法實作了 SQL/MM 規範。SQL-MM 3: 8.1.3, 9.5.4

可用性 2.0.0：引入了對地理的支援

範例：幾何

傳回 Polygon 和 MultiPolygon 的周長（以英尺為單位）。請注意，這是以英尺為單位，因為 EPSG:2249 是馬薩諸塞州平面英尺

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)
			

範例：地理

傳回 Polygon 和 MultiPolygon 的周長（以公尺和英尺為單位）。請注意，這是地理 (WGS 84 經緯度)

SELECT  ST_Perimeter(geog) As per_meters, ST_Perimeter(geog)/0.3048 As per_ft
FROM ST_GeogFromText('POLYGON((-71.1776848522251 42.3902896512902,-71.1776843766326 42.3903829478009,
-71.1775844305465 42.3903826677917,-71.1775825927231 42.3902893647987,-71.1776848522251 42.3902896512902))') As geog;

   per_meters    |      per_ft
-----------------+------------------
37.3790462565251 | 122.634666195949


-- MultiPolygon example --
SELECT  ST_Perimeter(geog) As per_meters, ST_Perimeter(geog,false) As per_sphere_meters,  ST_Perimeter(geog)/0.3048 As per_ft
FROM ST_GeogFromText('MULTIPOLYGON(((-71.1044543107478 42.340674480411,-71.1044542869917 42.3406744369506,
-71.1044553562977 42.340673886454,-71.1044543107478 42.340674480411)),
((-71.1044543107478 42.340674480411,-71.1044860600303 42.3407237015564,-71.1045215770124 42.3407653385914,
-71.1045498002983 42.3407946553165,-71.1045611902745 42.3408058316308,-71.1046016507427 42.340837442371,
-71.104617893173 42.3408475056957,-71.1048586153981 42.3409875993595,-71.1048736143677 42.3409959528211,
-71.1048878050242 42.3410084812078,-71.1044020965803 42.3414730072048,
-71.1039672113619 42.3412202916693,-71.1037740497748 42.3410666421308,
-71.1044280218456 42.3406894151355,-71.1044543107478 42.340674480411)))') As geog;

    per_meters    | per_sphere_meters |      per_ft
------------------+-------------------+------------------
 257.634283683311 |  257.412311446337 | 845.256836231335
			

另請參閱

ST_GeogFromText, ST_GeomFromText, ST_Length