SDO_UTIL.ELLIPSE

Format

SDO_UTIL.ELLIPSE_POLYGON(
     center_longitude IN NUMBER, 
     center_latitude  IN NUMBER, 
     semi_major_axis  IN NUMBER, 
     semi_minor_axis  IN NUMBER, 
     azimuth          IN NUMBER, 
     arc_tolerance    IN NUMBER 
     ) RETURN SDO_GEOMETRY;

Description

Returns the polygon geometry that approximates and is covered by a specified ellipse.

Parameters

center_longitude: Center longitude (in degrees) of the ellipse to be used to create the returned geometry.
center_latitude: Center latitude (in degrees) of the ellipse to be used to create the returned geometry.
semi_major_axis: Length (in meters) of the semi-major axis of the ellipse to be used to create the returned geometry.
semi_minor_axis: Length (in meters) of the semi-minor axis of the ellipse to be used to create the returned geometry.
azimuth: Number of degrees of the azimuth (clockwise rotation of the major axis from north) of the ellipse to be used to create the returned geometry. Must be from 0 to 180. The returned geometry is rotated by the specified number of degrees.
arc_tolerance: A numeric value to be used to construct the polygon geometry. The arc_tolerance parameter value has the same meaning and usage guidelines as the arc_tolerance keyword value in the params parameter string for the SDO_GEOM.SDO_ARC_DENSIFY function. The unit of measurement associated with the geometry is associated with the arc_tolerance parameter value. (For more information, see the Usage Notes for the SDO_GEOM.SDO_ARC_DENSIFY function in SDO_GEOM Package (Geometry).)

Usage Notes

This function is useful for creating an ellipse-like polygon around a specified center point when a true ellipse cannot be used (an ellipse is not valid for geodetic data with Oracle Spatial). The returned geometry has an SDO_SRID value of 8307 (for Longitude / Latitude (WGS 84)).

Examples

The following example returns an ellipse-like polygon, oriented east-west (azimuth = 90), around a point near the center of Concord, Massachusetts. An arc_tolerance value of 5 meters is used in computing the polygon vertices.

SELECT SDO_UTIL.ELLIPSE_POLYGON(-71.34937, 42.46101, 100, 50, 90, 5)
   FROM DUAL;
 
SDO_UTIL.ELLIPSE_POLYGON(-71.34937,42.46101,100,50,90,5)(SDO_GTYPE, SDO_SRID, SD
--------------------------------------------------------------------------------
SDO_GEOMETRY(2003, 8307, NULL, SDO_ELEM_INFO_ARRAY(1, 1003, 1), SDO_ORDINATE_ARR
AY(-71.350589, 42.46101, -71.350168, 42.4606701, -71.349708, 42.460578, -71.3493
7, 42.4605603, -71.349032, 42.460578, -71.348572, 42.4606701, -71.348151, 42.461
01, -71.348572, 42.4613499, -71.349032, 42.461442, -71.34937, 42.4614597, -71.34
9708, 42.461442, -71.350168, 42.4613499, -71.350589, 42.46101))