ST_Envelope - Amazon Redshift
SyntaxArgumentsReturn typeExamples

ST_Envelope

ST_Envelope returns the minimum bounding box of the input geometry, as follows:

  • If the input geometry is empty, the returned geometry is a copy of the input geometry.

  • If the minimum bounding box of the input geometry degenerates to a point, the returned geometry is a point.

  • If the minimum bounding box of the input geometry is one-dimensional, a two-point linestring is returned.

  • If none of the preceding is true, the function returns a clockwise-oriented polygon whose vertices are the corners of the minimum bounding box.

The spatial reference system identifier (SRID) of the returned geometry is the same as that of the input geometry.

For all nonempty input, the function operates on the 2D projection of the input geometry.

Syntax

ST_Envelope(geom)

Arguments

geom

A value of data type GEOMETRY or an expression that evaluates to a GEOMETRY type.

Return type

GEOMETRY

If geom is null, then null is returned.

Examples

The following SQL converts a well-known text (WKT) representation of a four-point LINESTRING to a GEOMETRY object and returns a polygon whose vertices whose corners are the minimum bounding box. 

SELECT ST_AsText(ST_Envelope(ST_GeomFromText('GEOMETRYCOLLECTION(POLYGON((0 0,10 0,0 10,0 0)),LINESTRING(20 10,20 0,10 0))')));

    st_astext
------------------------------------
  POLYGON((0 0,0 10,20 10,20 0,0 0))