Name
ST_Snap — Snaps the vertices and segments of a Geometry to another Geometry's vertices. A snapping distance tolerance is used to control where snapping is performed.
Synopsis
geometry ST_Snap(bytea GeomA, bytea GeomB, double
Tolerance);
Description
Snaps the vertices and segments of a Geometry to another Geometry's vertices. Improves robustness for overlay operations, by eliminating nearly parallel edges (which cause problems during noding and intersection calculation).
Coordinate Dimensions
| 2D | 3D | M |
|---|---|---|
 | | |
Spatial Standards Support
| OGC SFS for SQL. 1.1 (1999) | OGC SFS for SQL. 1.1.0 (2005) | OGC SFS for SQL. 1.2.0 (2006) | SQL-MM Part 3 |
|---|---|---|---|
| - | - | - | - |
Examples
--Ex. 1
SELECT ST_AsText(ST_SNAP(A,B,2)) As C FROM (
SELECT ST_GeomFromText('POLYGON ((1 1, 1 4, 4.5 6.8, 4.6 0.3, 1 1))') As A,
ST_GeomFromText('POLYGON ((6 2, 6 3, 8 3, 8 2, 6 2))') As B) as foo;
--Result
C
-------------------------------------------------------
POLYGON ((1 1, 1 4, 4.5 6.8, 6 3, 6 2, 4.6 0.3, 1 1))
--Ex. 2
SELECT ST_AsText(ST_SNAP(A,B,2)) As C FROM (
SELECT ST_GeomFromText('POLYGON ((1 1, 1 4, 4 4, 4 1, 1 1))') As A,
ST_GeomFromText('POLYGON ((5 0.7, 7 4.8, 8 3, 8 2, 5 0.7))') As B) as foo;
--Result:
C
POLYGON ((1 1, 1 4, 4 4, 5 0.7, 1 1)) |  |
 |  |