PostGIS
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.
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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 Constructs such as ST_AsBinary('POINT(1 2)') are no longer
valid and you will get an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
00000000000000000000000000SELECT ST_AsBinary(ST_GeomFromText('POLYGON((0 0,0 1,1 1,1 0,0 0))',4326), 'XDR');
st_asbinary
--------------------------------
\x000000000300000001000000050000000000000000000000000000000000000000000000003ff000
00000000003ff00000000000003ff00000000000003ff00000000000000000000000000000000000
00000000000000000000000000