[postgis-users] Checking Road Network Topology

[Miller, Stephan]

Thanks.

I have set up a new topo geometry in the "roads" table.  I am transforming the 4326 coordinates on-the-fly to 32648.

Do you see anything wrong with reusing the roads table for the processing?

Thanks,

Steve

From: postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-bounces at lists.osgeo.org] On Behalf Of toni hernández
Sent: Friday, January 23, 2015 2:52 AM
To: postgis-users at lists.osgeo.org
Subject: Re: [postgis-users] Checking Road Network Topology

Steve,

I transformed the geometries into a new table.
>From there I created a new topology using the new reference system (25831)
On 22/01/2015 16:35, Miller, Stephan wrote:
Thanks.

Here is the code as it now stands.  I was using 4326 and topology will not work for geography coordinates.  Can you share your code so that I can compare?  I am trying to do an on-the-fly transform to 32648 for each record in the line 26.  Is that how you approached this problem?

Thanks,

Steve


From: postgis-users-bounces at lists.osgeo.org<mailto:postgis-users-bounces at lists.osgeo.org> [mailto:postgis-users-bounces at lists.osgeo.org] On Behalf Of toni hernández
Sent: Thursday, January 22, 2015 10:14 AM
To: postgis-users at lists.osgeo.org<mailto:postgis-users at lists.osgeo.org>
Subject: Re: [postgis-users] Checking Road Network Topology

Steve,

I had the same issue when working with geometries using srid=4326 . I was also following the same link (http://blog.mathieu-leplatre.info/use-postgis-topologies-to-clean-up-road-networks.html)
Then I tried with some projected geometries (units = meters) and the problem was gone. I am not sure why. Maybe it was just a coincidence.

cheers.


On 20/01/2015 20:45, Miller, Stephan wrote:
All -

I am attempting to validate the topology of a dense road network ( 1.2 Million roads) modeled after http://blog.mathieu-leplatre.info/use-postgis-topologies-to-clean-up-road-networks.html from July 2013<http://blog.mathieu-leplatre.info/use-postgis-topologies-to-clean-up-road-networks.html%20from%20July%202013>.  The code is given below:


-- HC_RoadTopologicalCheck
-- Drop the existing topology

SELECT topology.DropTopology('roads_topo');

SELECT topology.CreateTopology('roads_topo',4326, 0.000001, true);

SELECT topology.AddTopoGeometryColumn('roads_topo', 'fgcm', 'transportationgroundcrv', 'topo_shape', 'LINESTRING');
--UPDATE transportationgroundcrv SET topo_shape = topology.toTopoGeom(transportationgroundcrv.shape, 'roads_topo', 1, 1.0);

-- Encapsulate the UPDATE inside code that checks for errors
DO $$ DECLARE r record;
BEGIN
    FOR r IN SELECT * FROM transportationgroundcrv loop
        BEGIN
            UPDATE transportationgroundcrv SET topo_shape = topology.toTopoGeom(transportationgroundcrv.shape, 'roads_topo', 1, 1.0)
            WHERE r.objectid = r.objectid;
        EXCEPTION
                WHEN OTHERS THEN
                RAISE WARNING 'Loading of record % failed: %', r.objectid, SQLERRM;
        END;
    END LOOP;

END$$;

Select * from ValidateTopology('roads_topo');

I am getting everything passing to the exception statement and all the records are being flagged with

WARNING:  Loading of record 791456 failed: SQL/MM Spatial exception - curve not simple

Intermittently, I am getting the following error also.

WARNING:  Loading of record 792591 failed: Spatial exception - geometry intersects edge 69612


Everything appears to be flagged as an error; the ValidateTopology call returns nothing.

Any insights or suggestions would be appreciated.

Steve







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