Re: converting points to circles

From: Benjamin Hell <bhell_at_spamfence.net>
Date: Wed, 09 Nov 2005 13:53:18 +0100
Message-ID: <3te9pvFs7l63U1@individual.net>

Hi Erik!

> we need to transform points in Oracle spatial to circles with a
> given radius in Oracle spatial.

The following function should do it. It is pretty rudimentary (e.g. no check whether input geometry is really a point), but could be a starting point. The closest built-in solution I know is SDO_GEOM.SDO_BUFFER() which creates a polygon shaped buffer zone around the point.

Regards,

Ben

• test table CREATE TABLE SPATIAL_TEST ( GEOMETRY SDO_GEOMETRY );
• test data INSERT INTO SPATIAL_TEST VALUES ( SDO_GEOMETRY ( 2001, NULL, NULL, SDO_ELEM_INFO_ARRAY (1, 1, 1), SDO_ORDINATE_ARRAY (10, 10) ) );
• function to convert point to circle CREATE OR REPLACE FUNCTION Point2Circle( point SDO_GEOMETRY, radius NUMBER) RETURN SDO_GEOMETRY IS BEGIN DECLARE xorig NUMBER; yorig NUMBER; circle SDO_GEOMETRY; BEGIN SELECT t.X, t.Y INTO xorig, yorig FROM SPATIAL_TEST s, TABLE (SDO_UTIL.GETVERTICES(s.GEOMETRY)) t; circle := SDO_GEOMETRY ( 2003, NULL, NULL, SDO_ELEM_INFO_ARRAY (1, 2003, 4), SDO_ORDINATE_ARRAY ( xorig - radius, yorig, xorig + radius, yorig,

                xorig, yorig + radius
            )
        );
        RETURN circle;

    END;
END;
/

• test it, radius = 5 SELECT GEOMETRY, Point2Circle(GEOMETRY, 5) FROM SPATIAL_TEST;
• clean up DROP TABLE SPATIAL_TEST; DROP FUNCTION Point2Circle;

Received on Wed Nov 09 2005 - 06:53:18 CST