Function

ST_Envelope

Introduction: This function returns the bounding box (envelope) of A. It's important to note that the bounding box is calculated using a cylindrical topology, not a spherical one. If the envelope crosses the antimeridian (the 180° longitude line), you can set the split parameter to true. This will return a Geography object containing two separate Polygon objects, split along that line.

Format:

ST_Envelope (A: Geography, splitAtAntiMeridian: Boolean)

Since: v1.8.0

SQL Example

SELECT ST_Envelope(ST_GeogFromWKT('MULTIPOLYGON (((177.285 -18.28799, 180 -18.28799, 180 -16.02088, 177.285 -16.02088, 177.285 -18.28799)), ((-180 -18.28799, -179.7933 -18.28799, -179.7933 -16.02088, -180 -16.02088, -180 -18.28799)))'), false);

Output:

POLYGON ((177.3 -18.3, -179.8 -18.3, -179.8 -16, 177.3 -16, 177.3 -18.3))

ST_AsEWKT

Introduction: Return the Extended Well-Known Text representation of a geography. EWKT is an extended version of WKT which includes the SRID of the geography. The format originated in PostGIS but is supported by many GIS tools.

Format: ST_AsEWKT (A: Geography)

Since: v1.8.0

SQL Example

SELECT ST_AsEWKT(ST_GeogFromWKT('LINESTRING (1 2, 3 4, 5 6)', 4326))

Output:

SRID=4326; LINESTRING (1 2, 3 4, 5 6)