ST_Simplify¶

Simplifies an input geometry or geography using the Douglas-Peucker algorithm.

Usage¶

geometry ST_Simplify(geom: geometry, tolerance: double)
geography ST_Simplify(geog: geography, tolerance: double)

Arguments¶

geog (geography): Input geography
tolerance (double)
geom (geometry): Input geometry

Description¶

Simplifies a geometry or geography using the Douglas-Peucker algorithm. The tolerance parameter controls the degree of simplification: higher values produce simpler geometries. For geography, the tolerance is specified in meters and a different algorithm is used.

This function may produce invalid geometries; use ST_SimplifyPreserveTopology when validity must be maintained.

Examples¶

SELECT ST_Simplify(
    ST_GeomFromWKT('LINESTRING (0 0, 0.5 0.1, 1 0, 1.5 0.1, 2 0)'),
    0.2
);

┌──────────────────────────────────────────────────────────────────────────────┐
│ st_simplify(st_geomfromwkt(Utf8("LINESTRING (0 0, 0.5 0.1, 1 0, 1.5 0.1, 2 0 │
│                              )")),Float64(0.2))…                             │
╞══════════════════════════════════════════════════════════════════════════════╡
│ LINESTRING(0 0,2 0)                                                          │
└──────────────────────────────────────────────────────────────────────────────┘

SELECT ST_Simplify(
    ST_GeogFromWKT('LINESTRING (0 0, 0.5 0.1, 1 0, 1.5 0.1, 2 0)'),
    50000
);

┌──────────────────────────────────────────────────────────────────────────────┐
│ st_simplify(st_geogfromwkt(Utf8("LINESTRING (0 0, 0.5 0.1, 1 0, 1.5 0.1, 2 0 │
│                              )")),Int64(50000))…                             │
╞══════════════════════════════════════════════════════════════════════════════╡
│ LINESTRING(0 0,2 0)                                                          │
└──────────────────────────────────────────────────────────────────────────────┘