The tools in Locator and Spatial do not include translate, rotate and scale functions. I have developed the first two of these and have written about them in the referenced articles. In this article I show how to use the last of these, a Scale function, which I have just developed.

Here is the function’s descriptive header and the public function declarations from my GEOM package.

  /* ----------------------------------------------------------------------------------------
  * function   : SCALE
  * precis     : Function which updates all coordinates in a shape by applying an x/y/z factor.
  * version    : 1.0
  * description: As against, move, which adds a supplied delta to existing coords, Scale multiplies
  *               existing coordinates by the supplied factors. Rounding is applied to the result using
  *               the supplied tolerances.
  * usage      : Function Scale( p_geometry IN MDSYS.SDO_GEOMETRY,
  *                               p_diminfo  IN MDSYS.SDO_DIM_ARRAY,
  *                               p_deltaX   IN number,
  *                               p_deltaY   IN number,
  *                               p_deltaY   IN number,
  *                             ) 
  *                 Return MDSYS.SDO_GEOMETRY DETERMINISTIC;
  *               eg fixedShape := CODESYS.geom.tolerance(shape,diminfo);
  * param      : p_geometry    : The shape to move.
  * paramtype  : p_geomery     : MDSYS.SDO_GEOMETRY
  * param      : p_diminfo     : Tolerance used to round x/y/z values after scaling 
  * param      : p_diminfo     : SDO_DIM_ARRAY 
  * param      : p_XFactor     : Factor to be applied to the X coordinate.
  * paramtype  : p_XFactor     : number
  * param      : p_YFactor     : Factor to be applied to the Y coordinate.
  * paramtype  : p_YFactor     : number
  * param      : p_ZFactor     : Factpr to be applied to the Z coordinate.
  * paramtype  : p_ZFactor     : number
  * requires   : CODESYS.GEOM.isMeasure and CODESYS.GEOM.ADD_Coordinate
  * return     : newShape      : Shape whose coordinates have been scaled.
  * rtnType    : newShape      : MDSYS.SDO_GEOMETRY
  * history    : Simon Greener - Jan 2008 - Original coding.
  * copyright  : Licensed under a Creative Commons Attribution-Share Alike 2.5 Australia License. (http://creativecommons.org/licenses/by-sa/2.5/au/) 
  **/
  FUNCTION Scale( p_geometry    IN MDSYS.SDO_GEOMETRY,
                  p_diminfo     IN MDSYS.SDO_DIM_ARRAY,
                  p_XFactor     IN NUMBER,
                  p_YFactor     IN NUMBER,
                  p_ZFactor     IN NUMBER  := NULL
                ) 
    Return MDSYS.SDO_GEOMETRY Deterministic;

  /* Wrapper functions */
  FUNCTION Scale( p_geometry    IN MDSYS.SDO_GEOMETRY,
                  p_tolerance   IN NUMBER,
                  p_XFactor     IN NUMBER,
                  p_YFactor     IN NUMBER,
                  p_ZFactor     IN NUMBER  := NULL
                ) 
    Return MDSYS.SDO_GEOMETRY Deterministic;

  FUNCTION ST_Scale( p_geometry    IN MDSYS.ST_GEOMETRY,
                     p_tolerance   IN NUMBER,
                     p_XFactor     IN NUMBER,
                     p_YFactor     IN NUMBER,
                     p_ZFactor     IN NUMBER  := NULL )
    Return MDSYS.ST_GEOMETRY DETERMINISTIC;

First, let’s scale a 2D ST_LINESTRING using one of the wrapper functions:

SELECT GEOM.ST_Scale(MDSYS.ST_GEOMETRY.FROM_WKT('LINESTRING(1 2, 1 1)'), 0.005, 0.5, 0.75).Get_WKT() as GEOM
  FROM DUAL;

GEOM
------------------------------
LINESTRING (0.5 1.5, 0.5 0.75)

1 rows selected

The result is as follows.

Scale simple, vertical, line.

Now, let’s test it using the two 2.5D test cases from the PostGIS online help for its ST_Scale function.

First, scale all three ordinates.

-- Scale X, Y, Z
SELECT GEOM.AsEWKT(GEOM.Scale(SDO_GEOMETRY(3002,null,null,sdo_elem_info_array(1,2,1),sdo_ordinate_array(1,2,3,1,1,1)), 0.005, 0.5, 0.75, 0.8)) as Geom
  FROM DUAL;

GEOM
---------------------------------------------------------------------------------------
LINESTRING XYZ ( LINESTRING(0.5 1.5 2.3999999999999999, 0.5 0.75 0.80000000000000004) )

1 rows selected

Then scale only the X,Y coords of a 2.5D geometry.

-- Scale X Y for a 2.5D geometry
SELECT GEOM.AsEWKT(GEOM.Scale(SDO_GEOMETRY(3002,null,null,sdo_elem_info_array(1,2,1),sdo_ordinate_array(1,2,3,1,1,1)), 0.005, 0.5, 0.75)) as GEOM
  FROM DUAL;

GEOM
--------------------------------------------------------
LINESTRING XYZ ( LINESTRING(0.5 1.5 3.0, 0.5 0.75 1.0) )

1 rows selected

The result, graphically, in both cases is the same as in the 2D graphic above.

Finally, let’s scale a simple polygon’s X and Y coordinates by 2.

SELECT GEOM.AsEWKT(GEOM.Scale(MDSYS.SDO_GEOMETRY(2003,null,null,sdo_elem_info_array(1,1003,4),sdo_ordinate_array(1,1,2,2,3,1)), 0.005, 2, 2)) as Geom 
  FROM DUAL;

GEOM
------------------------------------------------------
POLYGON XY ( CURVEPOLYGON(2.0 2.0, 4.0 4.0, 6.0 2.0) )

1 rows selected

The result is as shown.

Scale simple 2D polygon by 2