SDO_LRS.OFFSET_GEOM

Format

SDO_LRS.OFFSET_GEOM_SEGMENT(
     geom_segment  IN SDO_GEOMETRY, 
     start_measure IN NUMBER, 
     end_measure   IN NUMBER, 
     offset        IN NUMBER, 
     tolerance     IN NUMBER DEFAULT 1.0e-8 
     [, unit       IN VARCHAR2] 
     ) RETURN SDO_GEOMETRY;

or

SDO_LRS.OFFSET_GEOM_SEGMENT(
     geom_segment  IN SDO_GEOMETRY, 
     dim_array     IN SDO_DIM_ARRAY, 
     start_measure IN NUMBER, 
     end_measure   IN NUMBER, 
     offset        IN NUMBER 
     [, unit       IN VARCHAR2] 
     ) RETURN SDO_GEOMETRY;

Description

Returns the geometric segment at a specified offset from a geometric segment.

Parameters

geom_segment: Geometric segment (LRS segment) containing measure information.
dim_array: Dimensional information array corresponding to geom_segment, usually selected from one of the xxx_SDO_GEOM_METADATA views (described in Geometry Metadata Views).
start_measure: Start measure of geom_segment at which to start the offset operation.
end_measure: End measure of geom_segment at which to start the offset operation.
offset: Distance to measure perpendicularly from the points along geom_segment. Positive offset values are to the left of geom_segment; negative offset values are to the right of geom_segment.
tolerance: Tolerance value (see Tolerance and Tolerance Values with LRS Functions). The default value is 0.00000001.
unit: Unit of measurement specification: a quoted string with one or both of the following keywords:

unit and an SDO_UNIT value from the MDSYS.SDO_DIST_UNITS table. See Unit of Measurement Support for more information about unit of measurement specification.
arc_tolerance and an arc tolerance value. See the Usage Notes for the SDO_GEOM.SDO_ARC_DENSIFY function in SDO_GEOM Package (Geometry) for more information about the arc_tolerance keyword.

For example: 'unit=km arc_tolerance=0.05'

If the input geometry is geodetic data, this parameter is required, and arc_tolerance must be specified. If the input geometry is Cartesian or projected data, arc_tolerance has no effect and should not be specified.

If this parameter is not specified for a Cartesian or projected geometry, or if the arc_tolerance keyword is specified for a geodetic geometry but the unit keyword is not specified, the unit of measurement associated with the data is assumed.

Usage Notes

start_measure and end_measure can be any points on the geometric segment. They do not have to be in any specific order. For example, start_measure and end_measure can be 5 and 10, respectively, or 10 and 5, respectively.

The direction and measures of the resulting geometric segment are preserved (that is, they reflect the original segment).

The geometry type of geom_segment must be line or multiline. For example, it cannot be a polygon.

An exception is raised if geom_segment, start_measure, or end_measure is invalid.

Examples

The following example returns the geometric segment 2 distance units to the left (positive offset 2) of the segment from measures 5 through 10 of Route 1. Note in SDO_ORDINATE_ARRAY of the returned segment that the Y values (6) are 2 greater than the Y values (4) of the relevant part of the original segment. (This example uses the definitions from the example in Example of LRS Functions.)

-- Create a segment offset 2 to the left from measures 5 through 10.
-- First, display the original segment; then, offset.
SELECT a.route_geometry FROM lrs_routes a WHERE a.route_id = 1;

ROUTE_GEOMETRY(SDO_GTYPE, SDO_SRID, SDO_POINT(X, Y, Z), SDO_ELEM_INFO, SDO_ORDIN
--------------------------------------------------------------------------------
SDO_GEOMETRY(3302, NULL, NULL, SDO_ELEM_INFO_ARRAY(1, 2, 1), SDO_ORDINATE_ARRAY(
2, 2, 0, 2, 4, 2, 8, 4, 8, 12, 4, 12, 12, 10, 18, 8, 10, 22, 5, 14, 27))        
                                                                                
SELECT  SDO_LRS.OFFSET_GEOM_SEGMENT(a.route_geometry, m.diminfo, 5, 10, 2)
    FROM lrs_routes a, user_sdo_geom_metadata m
    WHERE m.table_name = 'LRS_ROUTES' AND m.column_name = 'ROUTE_GEOMETRY'
      AND a.route_id = 1;

SDO_LRS.OFFSET_GEOM_SEGMENT(A.ROUTE_GEOMETRY,M.DIMINFO,5,10,2)(SDO_GTYPE, SDO_SR
--------------------------------------------------------------------------------
SDO_GEOMETRY(3302, NULL, NULL, SDO_ELEM_INFO_ARRAY(1, 2, 1), SDO_ORDINATE_ARRAY(
5, 6, 5, 10, 6, 10))