PostGIS
Description
Returns the polygon representation of the extent of the raster in spatial coordinate units defined by srid. It is a float8 minimum bounding box represented as a polygon.
The polygon is defined by the corner points of the bounding box
MINX, MINY), (MINX, MAXY), (MAXX, MAXY), (MAXX, MINY), (MINX, MINY
Examples
SELECT rid, ST_AsText(ST_Envelope(rast)) As envgeomwkt
FROM dummy_rast;
rid | envgeomwkt
-----+--------------------------------------------------------------------
1 | POLYGON((0 0,20 0,20 60,0 60,0 0))
2 | POLYGON((3427927 5793243,3427928 5793243,
3427928 5793244,3427927 5793244, 3427927 5793243))