ST_SubDivide
Signatures
GEOMETRY ST_SubDivide(GEOMETRY geom);
GEOMETRY ST_SubDivide(GEOMETRY geom, INTEGER max_vertices);
Description
Divides geometry (geom) into parts using its internal envelope, until each part can be represented using no more than max_vertices.
Where:
max_vertices: maximum number of vertices in the resulting geometry
Examples
With a LINESTRING
SELECT ST_subdivide('LINESTRING (1 1, 5 5)');
-- Answer: GEOMETRYCOLLECTION (POINT (3 3),
-- LINESTRING (3 3, 5 5),
-- LINESTRING (1 1, 3 3),
-- POINT (3 3))
With a POLYGON
SELECT st_SubDivide('POLYGON((1 2, 1 6, 5 6, 5 5, 7 5, 7 1, 3 1, 3 2, 1 2))',6);
-- Answer: MULTIPOLYGON (((1 3.5, 1 6, 4 6, 4 3.5, 1 3.5)),
-- ((4 3.5, 4 6, 5 6, 5 5, 7 5, 7 3.5, 4 3.5)),
-- ((1 2, 1 3.5, 4 3.5, 4 1, 3 1, 3 2, 1 2)),
-- ((4 1, 4 3.5, 7 3.5, 7 1, 4 1)))
With a POLYGON having a hole
SELECT st_SubDivide('POLYGON((1 2, 1 6, 5 6, 5 5, 7 5, 7 1, 3 1, 3 2, 1 2),
(3 3, 3 4, 4 4, 4 3, 3 3))',6);
-- Answer: GEOMETRYCOLLECTION (
-- LINESTRING (4 4, 4 3.5),
-- POLYGON ((1 3.5, 1 6, 4 6, 4 4, 3 4, 3 3.5, 1 3.5)),
-- LINESTRING (4 3.5, 4 3),
-- POLYGON ((4 1, 4 3, 4 3.5, 7 3.5, 7 1, 4 1)),
-- POLYGON ((1 2.25, 1 3.5, 2.5 3.5, 2.5 2.25, 1 2.25)),
-- POLYGON ((2.5 2.25, 2.5 3.5, 3 3.5, 3 3, 4 3, 4 2.25, 2.5 2.25)),
-- POLYGON ((1 2, 1 2.25, 2.5 2.25, 2.5 2, 1 2)),
-- POLYGON ((2.5 2, 2.5 2.25, 4 2.25, 4 1, 3 1, 3 2, 2.5 2)),
-- POLYGON ((4 4.75, 4 6, 5 6, 5 5, 5.5 5, 5.5 4.75, 4 4.75)),
-- POLYGON ((5.5 4.75, 5.5 5, 7 5, 7 4.75, 5.5 4.75)),
-- POLYGON ((4 3.5, 4 4, 4 4.75, 5.5 4.75, 5.5 3.5, 4 3.5)),
-- POLYGON ((5.5 3.5, 5.5 4.75, 7 4.75, 7 3.5, 5.5 3.5)))
