15.10 - Make_2D - Teradata Database

Teradata Database SQL Geospatial Types

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

Converts a 3D ST_Geometray value to a 2D ST_Geometry value, and optionally validates that the 2D geometry is well formed. This method strips the z coordinate from 3D geometries.

 

Argument …

Specifies …

validate

an INTEGER value that determines whether the converted 2D geometry is tested to ensure it is well formed:

  • If validate is 1, the 2D geometry is tested. If it is not well formed, Teradata Database returns an error.
  • If validate is not equal to 1 or is not specified, the 2D geometry is not tested.
  • Returns the 2D version of the ST_Geometry value on which the method is called.

    All ST_Geometry types.

  • The ST_IsValid method can be used to validate converted 2D geometries that were not validated by Make_2D.
  • If the input geometry is already a 2D geometry value, this value is returned unchanged by this method.
  • A well-formed 3D geometry value can become invalid during a 3D to 2D conversion. For example, if a 3D polygon lies in a plane parallel to the y axis, its line segments will self-intersect. Make_2D does not attempt to change the geometry type of the converted geometry from polygon to linestring to account for this, and an invalid 2D geometry can result.
  •    SELECT shape.Make_2D()
       FROM sample_shapes;