15.10 - SimplifyPreserveTopology - Teradata Database

Teradata Database SQL Geospatial Types

prodname
Teradata Database
vrm_release
15.10
category
Programming Reference
featnum
B035-1181-151K

Simplifies a geometry by removing points that would fall within a specified distance tolerance.

 

Argument …

Specifies …

tolerance

a FLOAT that represents the distance tolerance for the simplification. The simplified line will never be farther away from the original line than the tolerance value.

Returns an ST_Geometry value.

This method is valid on the following 2D geometries: LineString, MultiLineString, Polygon, and MultiPolygon. It is valid on these types within GeometryCollections.

If SimplfyPreserveTopology is called on other 2D geometries, those geometries are returned unchanged.

This method is not valid on 3D geometries.

  • The simplification always returns a valid geometry.
  • Simplified geometries require less storage space and fewer spatial operations during geospatial manipulations. Consequently operations on simplified geometries generally perform faster.
  • Smaller tolerance values result in a geometry closer to the input geometry, but will remove fewer vertices. Larger tolerance values will remove more vertices, but the resulting simplified geometry will be less similar to the original input.
  •    SELECT shape.SimplifyPreserveTopology(0.1)
       FROM sample_shapes;