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# ST_Polygonize

Generates a GeometryCollection composed of polygons that are formed from the linework of an input GeometryCollection. When the input does not contain any linework that forms a polygon, the function will return an empty GeometryCollection.

<img src="https://mintcdn.com/wherobots/wLm_IRUSNlHZTHJP/images/sql-functions/ST_Polygonize/ST_Polygonize.svg?fit=max&auto=format&n=wLm_IRUSNlHZTHJP&q=85&s=0474e0318a1ad66bb897ef1db35da941" alt="ST_Polygonize" width="500" height="300" data-path="images/sql-functions/ST_Polygonize/ST_Polygonize.svg" />

<Note>
  `ST_Polygonize` function assumes that the input geometries form a valid and simple closed linestring that can be turned into a polygon. If the input geometries are not noded or do not form such linestrings, the resulting GeometryCollection may be empty or may not contain the expected polygons.
</Note>

## Signatures

```sql theme={"system"}
ST_Polygonize(geom: Geometry)
```

## Parameters

<ParamField body="geom" type="Geometry" required>
  The input geometry.
</ParamField>

## Return type

<ResponseField type="Geometry">
  The resulting geometry.
</ResponseField>

## Example

```sql theme={"system"}
SELECT ST_AsText(ST_Polygonize(ST_GeomFromEWKT('GEOMETRYCOLLECTION (LINESTRING (2 0, 2 1, 2 2), LINESTRING (2 2, 2 3, 2 4), LINESTRING (0 2, 1 2, 2 2), LINESTRING (2 2, 3 2, 4 2), LINESTRING (0 2, 1 3, 2 4), LINESTRING (2 4, 3 3, 4 2))')));
```

```
GEOMETRYCOLLECTION (POLYGON ((0 2, 1 3, 2 4, 2 3, 2 2, 1 2, 0 2)), POLYGON ((2 2, 2 3, 2 4, 3 3, 4 2, 3 2, 2 2)))
```