ST_Snap¶

Introduction: Snaps the vertices and segments of the input geometry to reference geometry within the specified tolerance distance. The tolerance parameter controls the maximum snap distance.

If the minimum distance between the geometries exceeds the tolerance, the input geometry is returned unmodified. Adjusting the tolerance value allows tuning which vertices should snap to the reference and which remain untouched.

Return type: Geometry

Since: v1.6.0

Format: ST_Snap(input: Geometry, reference: Geometry, tolerance: double)

Input geometry:

ST_Snap base example

SQL Example:

SELECT
    ST_Snap(poly, line, ST_Distance(poly, line) * 1.01) AS polySnapped FROM (
        SELECT ST_GeomFromWKT('POLYGON ((236877.58 -6.61, 236878.29 -8.35, 236879.98 -8.33, 236879.72 -7.63, 236880.35 -6.62, 236877.58 -6.61), (236878.45 -7.01, 236878.43 -7.52, 236879.29 -7.50, 236878.63 -7.22, 236878.76 -6.89, 236878.45 -7.01))') as poly,
           ST_GeomFromWKT('LINESTRING (236880.53 -8.22, 236881.15 -7.68, 236880.69 -6.81)') as line
)

Output:

ST_Snap applied example

POLYGON ((236877.58 -6.61, 236878.29 -8.35, 236879.98 -8.33, 236879.72 -7.63, 236880.69 -6.81, 236877.58 -6.61), (236878.45 -7.01, 236878.43 -7.52, 236879.29 -7.5, 236878.63 -7.22, 236878.76 -6.89, 236878.45 -7.01))