SDO_SAM.SIMPLIFY

Format

SDO_SAM.SIMPLIFY_GEOMETRY(
     geom                  IN SDO_GEOMETRY, 
     dim                   IN SDO_DIM_ARRAY, 
     pct_area_change_limit IN NUMBER DEFAULT 2 
     ) RETURN SDO_GEOMETRY;

or

SDO_SAM.SIMPLIFY_GEOMETRY(
     geom                  IN SDO_GEOMETRY, 
     tol                   IN NUMBER, 
     pct_area_change_limit IN NUMBER DEFAULT 2 
     ) RETURN SDO_GEOMETRY;

Description

Simplifies a geometry.

Parameters

geom: Geometry to be simplified.
dim: Dimensional array for the geometry to be simplified.
tol: Tolerance value (see Tolerance).
pct_area_change_limit: The percentage of area changed to be used for each simplification iteration, as explained in the Usage Notes.

Usage Notes

This function reduces the number of vertices in a geometry by internally applying the SDO_UTIL.SIMPLIFY function (documented in SDO_LRS Package (Linear Referencing System)) with an appropriate threshold value.

Reducing the number of vertices may result in a change in the area of the geometry. The pct_area_change_limit parameter specifies how much area change can be tolerated while simplifying the geometry. It is usually a number from 1 to 100. The default value is 2; that is, the area of the geometry can either increase or decrease by at most two percent compared to the original geometry as a result of the geometry simplification.

Examples

The following example simplifies the geometries in the GEOMETRY column of the POLY_4PT_TEMP table.

SELECT sdo_sam.simplify_geometry(a.geometry, 0.00000005)
  FROM poly_4pt_temp a, user_sdo_geom_metadata b
  WHERE b.table_name='POLY_4PT_TEMP' ;
 
SDO_SAM.SIMPLIFY_GEOMETRY(A.GEOMETRY,0.00000005)(ORIG_AREA, CUR_AREA, ORIG_LEN,
--------------------------------------------------------------------------------
SDO_SMPL_GEOMETRY(28108.5905, 28108.5905, 758.440118, 758.440118, SDO_GEOMETRY(2
003, 8307, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARRAY(-122.4215,
37.7862, -122.422, 37.7869, -122.421, 37.789, -122.42, 37.7866, -122.4215, 37.78
62)))
 
SDO_SMPL_GEOMETRY(4105.33806, 4105.33806, 394.723053, 394.723053, SDO_GEOMETRY(2
003, 8307, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARRAY(-122.4019,
37.8052, -122.4027, 37.8055, -122.4031, 37.806, -122.4012, 37.8052, -122.4019, 3
7.8052)))
   . 
   . 
   . 
50 rows selected.