PolarDB:ST_MapMatching

Syntax

geometry ST_MapMatching(text wsname, geometry geom, text options);
geometry ST_MapMatching(text wsname, trajectory traj, text options);

Parameters

Return values

Returns the road geometric objects that corresponds to input geometric objects or trajectories.

Description

• You can enter geometric line objects or trajectory objects for matching.

• If you specify a trajectory object, the geometry objects in the trajectory object are matched and new matched geometry objects are returned. However, the attribute information of the trajectory objects is not returned.

• The function returns new geometric objects that consist of a sequence of segments that corresponds to the input geometric objects.

Examples

1. Prepare road network data and build the road network topology.

   CREATE TABLE network (fid bigint, -- The unique identifier of the road segment.
                            source bigint, -- The start node identifier of the road segment.
                            target bigint, -- The end node identifier of the road segment.
                            cost double precision, - The road weight value (not currently used).
                            geom public.geometry(LineString,4326) -- The geometric objects of the road segment.
   );
   
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(1, 1, 2,1, st_geomfromtext('LINESTRING(2 1,2 0)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(2, 2, 1,1, st_geomfromtext('LINESTRING(2 0,2 1)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(3, 3, 1,1, st_geomfromtext('LINESTRING(3 1,2 1)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(4, 4, 3,1, st_geomfromtext('LINESTRING(4 1,3 1)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(5, 1, 5,1, st_geomfromtext('LINESTRING(2 1,2 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(6, 5, 1,1, st_geomfromtext('LINESTRING(2 2,2 1)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(7, 3, 6,1, st_geomfromtext('LINESTRING(3 1,3 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(8, 7, 8,1, st_geomfromtext('LINESTRING(0 2,1 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(9, 8, 7,1, st_geomfromtext('LINESTRING(1 2,0 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(10,5, 8,3, st_geomfromtext('LINESTRING(2 2,1 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(11,8, 5,3, st_geomfromtext('LINESTRING(1 2,2 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(12,6, 5,1, st_geomfromtext('LINESTRING(3 2,2 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(13,5, 6,1, st_geomfromtext('LINESTRING(2 2,3 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(14,6, 9,1, st_geomfromtext('LINESTRING(3 2,4 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(15,9, 6,1, st_geomfromtext('LINESTRING(4 2,3 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(16,10,5,1, st_geomfromtext('LINESTRING(2 3,2 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(17,5, 10,1, st_geomfromtext('LINESTRING(2 2,2 3)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(18,6, 11,1, st_geomfromtext('LINESTRING(3 2,3 3)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(19,10,11,1, st_geomfromtext('LINESTRING(2 3,3 3)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(20,11,12,1, st_geomfromtext('LINESTRING(3 3,4 3)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(21,13,10,1, st_geomfromtext('LINESTRING(2 4,2 3)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(22,10,13,1, st_geomfromtext('LINESTRING(2 3,2 4)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(23,9, 12,1, st_geomfromtext('LINESTRING(4 2,4 3)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(24,12,9,1, st_geomfromtext('LINESTRING(4 3,4 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(25,9, 4,1, st_geomfromtext('LINESTRING(4 2,4 1)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(26,4, 9,1, st_geomfromtext('LINESTRING(4 1,4 2)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(27,14,15,1, st_geomfromtext('LINESTRING(0.5 3.5,2 3.5)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(28,15,14,1, st_geomfromtext('LINESTRING(2 3.5,0.5 3.5)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(29,16,17,1, st_geomfromtext('LINESTRING(3.5 4,3.5 2.3)'));
   INSERT INTO network(fid, source, target, cost, geom)
   VALUES(30,17,16,1, st_geomfromtext('LINESTRING(3.5 2.3,3.5 4)'));
   
   SELECT st_createworkspace('mm_ws_test1', 'select fid, source, target, geom from network');
   
   CREATE TABLE traj(id int, geom geometry(linestring, 4326));
   INSERT INTO traj(id, geom)
   VALUES(1,st_geomfromtext('LINESTRING(4.15 1.6,3.47 0.92,2.4 0.92,2.14 1.53,2.14 2.57,2.49 2.98)'));

2. Perform road matching.

   SELECT ST_AsText(ST_MapMatching('mm_ws_test', ST_GeomFromText('LINESTRING(4.15 1.6,3.47 0.92,2.4 0.92,2.14 1.53,2.14 2.57,2.49 2.98)'), '{"algorithm":"stmatch","k":4,"r":0.25,"e":0.5}'::text));

   Sample result:

                        geom                     
   ----------------------------------------------
    LINESTRING(4 1.6,4 1,3 1,2 1,2 2,2 3,2.49 3)
   (1 row)