This topic describes the ST_Envelope function. This function returns the bounding box of the input geometry object.
Syntax
geometry ST_Envelope(geometry g1);Parameters
| Parameter | Description |
|---|---|
| g1 | The geometry object that you want to specify. |
Description
- The value of the bounding box is in the FLOAT8 data type.
- A bounding box is represented as a polygon object and the bounding box is defined by the corner points of the polygon object. Format of corner points: (MINX,MINY),(MINX,MAXY),(MAXX,MAXY),(MAXX,MINY),(MINX,MINY).
- If you specify a vertical line or a point, this function returns a geometry object of a lower dimension than a polygon object, such as a point object or a LineString object. This is a degenerate case.
Examples
- Results returned by using the default parameter settings:
SELECT ST_AsText(ST_Envelope('LINESTRING(0 0,2 2)'::geometry )); st_astext -------------------------------- POLYGON((0 0,0 2,2 2,2 0,0 0)) (1 row) - Results returned in a degenerate case:
SELECT ST_AsText(ST_Envelope('LINESTRING(0 0,0 2)'::geometry )); st_astext --------------------- LINESTRING(0 0,0 2) (1 row)