This topic describes the ST_MakePolygon function. This function constructs a polygon object by using shells.
Syntax
geometry ST_MakePolygon(geometry linestring);
geometry ST_MakePolygon(geometry outerlinestring , geometry[] interiorlinestrings);Parameters
| Parameter | Description |
|---|---|
| linestring | The LineString object that represents the shell. |
| outerlinestring | The LineString object that represents the outer shell. |
| interiorlinestrings | The LineString object that represents the inner shell. |
Description
You can specify only a closed LineString.
Examples
- Construct a polygon object by using the default parameter settings.
SELECT ST_AsText(ST_MakePolygon(ST_GeomFromText('LINESTRING(1 2,3 4,5 6,1 2)'))); st_astext ---------------------------- POLYGON((1 2,3 4,5 6,1 2)) (1 row) - Construct a polygon object that has an inner shell.
SELECT ST_AsText(ST_MakePolygon(ST_GeomFromText('LINESTRING(0 0,0 1,1 1,0 0)'),ARRAY[ST_GeomFromText('LINESTRING(-1 -1,-1 2,2 2,-1 -1)')])); st_astext --------------------------------------------------- POLYGON((0 0,0 1,1 1,0 0),(-1 -1,-1 2,2 2,-1 -1)) (1 row)