PostGIS
Description
Returns a valid geometry with all points rounded to the provided grid tolerance, and features below the tolerance removed.
Unlike ST_SnapToGrid the returned geometry will be valid, with no ring self-intersections or collapsed components.
Precision reduction can be used to:
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match coordinate precision to the data accuracy
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reduce the number of coordinates needed to represent a geometry
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ensure valid geometry output to formats which use lower precision (e.g. text formats such as WKT, GeoJSON or KML when the number of output decimal places is limited).
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export valid geometry to systems which use lower or limited precision (e.g. SDE, Oracle tolerance value)
Availability: 3.1.0 - requires GEOS >= 3.9.0.
Examples
SELECT ST_AsText(ST_ReducePrecision('POINT(1.412 19.323)', 0.1));
st_astext
-----------------
POINT(1.4 19.3)
SELECT ST_AsText(ST_ReducePrecision('POINT(1.412 19.323)', 1.0));
st_astext
-------------
POINT(1 19)
SELECT ST_AsText(ST_ReducePrecision('POINT(1.412 19.323)', 10));
st_astext
-------------
POINT(0 20)Precision reduction can reduce number of vertices
SELECT ST_AsText(ST_ReducePrecision('LINESTRING (10 10, 19.6 30.1, 20 30, 20.3 30, 40 40)', 1));
st_astext
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LINESTRING (10 10, 20 30, 40 40)Precision reduction splits polygons if needed to ensure validity
SELECT ST_AsText(ST_ReducePrecision('POLYGON ((10 10, 60 60.1, 70 30, 40 40, 50 10, 10 10))', 10));
st_astext
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MULTIPOLYGON (((60 60, 70 30, 40 40, 60 60)), ((40 40, 50 10, 10 10, 40 40)))