PostGIS
Description
An aggregate function that returns a box2d bounding box that bounds a set of geometries.
The bounding box coordinates are in the spatial reference system of the input geometries.
ST_Extent is similar in concept to Oracle Spatial/Locator’s SDO_AGGR_MBR.
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Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.
This
function supports Polyhedral surfaces.
This
function supports Triangles and Triangulated Irregular Network Surfaces
(TIN).
Examples
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SELECT ST_Extent(geom) as bextent FROM sometable;
st_bextent
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BOX(739651.875 2908247.25,794875.8125 2970042.75)
--Return extent of each category of geometries
SELECT ST_Extent(geom) as bextent
FROM sometable
GROUP BY category ORDER BY category;
bextent | name
----------------------------------------------------+----------------
BOX(778783.5625 2951741.25,794875.8125 2970042.75) | A
BOX(751315.8125 2919164.75,765202.6875 2935417.25) | B
BOX(739651.875 2917394.75,756688.375 2935866) | C
--Force back into a geometry
-- and render the extended text representation of that geometry
SELECT ST_SetSRID(ST_Extent(geom),2249) as bextent FROM sometable;
bextent
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SRID=2249;POLYGON((739651.875 2908247.25,739651.875 2970042.75,794875.8125 2970042.75,
794875.8125 2908247.25,739651.875 2908247.25))