ST_AsBinary
Name
ST_AsBinary — Return the OGC/ISO Well-Known Binary (WKB) representation of the geometry/geography without SRID meta data.
Synopsis
bytea
ST_AsBinary
(
geometry
g1
)
;
bytea
ST_AsBinary
(
geometry
g1
, text
NDR_or_XDR
)
;
bytea
ST_AsBinary
(
geography
g1
)
;
bytea
ST_AsBinary
(
geography
g1
, text
NDR_or_XDR
)
;
Description
Returns the OGC/ISO Well-Known Binary (WKB) representation of the geometry. The first function variant defaults to encoding using server machine endian. The second function variant takes a text argument specifying the endian encoding, either little-endian ('NDR') or big-endian ('XDR').
WKB format is useful to read geometry data from the database and maintaining full numeric precision. This avoids the precision rounding that can happen with text formats such as WKT.
To perform the inverse conversion of WKB to PostGIS geometry use ST_GeomFromWKB .
![[Note]](./images/note.png)
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The OGC/ISO WKB format does not include the SRID. To get the EWKB format which does include the SRID use ST_AsEWKB |
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The default behavior in PostgreSQL 9.0 has been changed to output bytea in hex encoding. If your GUI tools require the old behavior, then SET bytea_output='escape' in your database. |
Enhanced: 2.0.0 support for Polyhedral surfaces, Triangles and TIN was introduced.
Enhanced: 2.0.0 support for higher coordinate dimensions was introduced.
Enhanced: 2.0.0 support for specifying endian with geography was introduced.
Availability: 1.5.0 geography support was introduced.
Changed: 2.0.0 Inputs to this function can not be unknown -- must be geometry. Constructs such as
ST_AsBinary('POINT(1 2)')
are no longer valid and you will get an
n st_asbinary(unknown) is not unique error
. Code like that
needs to be changed to
ST_AsBinary('POINT(1 2)'::geometry);
. If that is not possible, then install
legacy.sql
.
This method implements the
OGC Simple Features
Implementation Specification for SQL 1.1.
s2.1.1.1
This method implements the SQL/MM specification.
SQL-MM 3: 5.1.37
This method supports Circular Strings and Curves.
This function supports Polyhedral surfaces.
This function supports Triangles and Triangulated Irregular Network Surfaces (TIN).
This function supports 3d and will not drop the z-index.
Examples
SELECT ST_AsBinary(ST_GeomFromText('POLYGON((0 0,0 1,1 1,1 0,0 0))',4326));
st_asbinary
--------------------------------
\x01030000000100000005000000000000000000000000000000000000000000000000000000000000
000000f03f000000000000f03f000000000000f03f000000000000f03f0000000000000000000000
00000000000000000000000000
SELECT ST_AsBinary(ST_GeomFromText('POLYGON((0 0,0 1,1 1,1 0,0 0))',4326), 'XDR');
st_asbinary
--------------------------------
\x000000000300000001000000050000000000000000000000000000000000000000000000003ff000
00000000003ff00000000000003ff00000000000003ff00000000000000000000000000000000000
00000000000000000000000000