ST_Segmentize
Name
ST_Segmentize — Return a modified geometry/geography having no segment longer than the given distance. Distance computation is performed in 2d only. For geometry, length units are in units of spatial reference. For geography, units are in meters.
Synopsis
geometry
ST_Segmentize
(
geometry
geom
, float
max_segment_length
)
;
geography
ST_Segmentize
(
geography
geog
, float
max_segment_length
)
;
Description
Returns a modified geometry having no segment longer than the
given
max_segment_length
. Distance computation is performed in 2d
only. For geometry, length units are in units of spatial reference. For geography, units are in meters.
Availability: 1.2.2
Enhanced: 2.1.0 support for geography was introduced.
Changed: 2.1.0 As a result of the introduction of geography support: The construct
SELECT ST_Segmentize('LINESTRING(1 2, 3 4)',0.5);
will result in ambiguous function error. You need to have properly typed object e.g. a geometry/geography column, use ST_GeomFromText, ST_GeogFromText or
SELECT ST_Segmentize('LINESTRING(1 2, 3 4)'::geometry,0.5);
![[Note]](images/note.png)
|
|
|
This will only increase segments. It will not lengthen segments shorter than max length |
Examples
SELECT ST_AsText(ST_Segmentize(
ST_GeomFromText('MULTILINESTRING((-29 -27,-30 -29.7,-36 -31,-45 -33),(-45 -33,-46 -32))')
,5)
);
st_astext
--------------------------------------------------------------------------------------------------
MULTILINESTRING((-29 -27,-30 -29.7,-34.886615700134 -30.758766735029,-36 -31,
-40.8809353009198 -32.0846522890933,-45 -33),
(-45 -33,-46 -32))
(1 row)
SELECT ST_AsText(ST_Segmentize(ST_GeomFromText('POLYGON((-29 28, -30 40, -29 28))'),10));
st_astext
-----------------------
POLYGON((-29 28,-29.8304547985374 37.9654575824488,-30 40,-29.1695452014626 30.0345424175512,-29 28))
(1 row)