SDO_UTIL.REMOVE_DUPLICATE

Format

SDO_UTIL.REMOVE_DUPLICATE_VERTICES(
     geometry  IN SDO_GEOMETRY, 
     tolerance IN NUMBER 
     ) RETURN SDO_GEOMETRY;

Description

Removes duplicate (redundant) vertices from a geometry.

Parameters

geometry: Geometry from which to remove duplicate vertices.
tolerance: Tolerance value (see Tolerance).

Usage Notes

When two consecutive vertices in a geometry are the same or within the tolerance value associated with the geometry, Spatial considers the geometry to be invalid. The Spatial geometry validation functions return the error ORA-13356 in these cases. You can use the REMOVE_DUPLICATE_VERTICES function to change such invalid geometries into valid geometries.

This function also closes polygons so that the first vertex of the ring is the same as the last vertex of the ring.

This function is not supported for any point geometries (including oriented points).

If the input geometry does not contain any duplicate vertices, it is returned.

Examples

The following example removes a duplicate vertex from the input geometry, which is the same geometry as cola_b (see Simple Example: Inserting_ Indexing_ and Querying Spatial Data) except that it has been deliberately made invalid by adding a third vertex that is the same point as the second vertex (8,1).

SELECT SDO_UTIL.REMOVE_DUPLICATE_VERTICES(
  SDO_GEOMETRY(
    2003,  -- two-dimensional polygon
    NULL,
    NULL,
    SDO_ELEM_INFO_ARRAY(1,1003,1), -- one polygon (exterior polygon ring)
    SDO_ORDINATE_ARRAY(5,1, 8,1, 8,1, 8,6, 5,7, 5,1) -- 2nd and 3rd points
                                                -- are duplicates.
  ),
  0.005 -- tolerance value
) FROM DUAL;

SDO_UTIL.REMOVE_DUPLICATE_VERTICES(SDO_GEOMETRY(2003,--TWO-DIMENSIONALPOLYGONNUL
--------------------------------------------------------------------------------
SDO_GEOMETRY(2003, NULL, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARR
AY(5, 1, 8, 1, 8, 6, 5, 7, 5, 1))