Re: [postgis-users] postgis topology

[Ludovic Granjon]

Hello

I think, I can do
SELECT st_geometryN(geom,1) FROM ec;
without error
I get

"POLYGON((504935.641400002 2310827.805,504952.193899997 
2310825.6349,504964.4124 2310824.033,504964.191799998 
2310823.56,504964.037199996 2310822.9832,504963.987400003 
2310822.5117,504948.949900001 2310822.7941,504940.407399997 
2310823.3589,504932.090300001 2310824.5769,504931.797399998 
2310824.7718,504931.360100001 2310824.9757,504930.894100003 
2310825.1006,504930.735399999 2310825.1239,504929.7368 
2310825.2555,504929.7368 2310825.8138,504929.847599998 
2310828.5646,504935.641400002 2310827.805))"

Thanks

Ludovic



Le 15/01/2014 10:47, Christophe Vergon a écrit :
Hello,

Is st_geometryN(r.geomp,1)  a valid geometry ?



Ludovic Granjon a écrit :
Hello (Bonjour Christophe)

I don't use french cadastre, only specific archaelogical data.

Thanks for this, I try but, I don't realy understand how worked 
topogeo_addpolygon.
If I do :

CREATE EXTENSION postgis;
CREATE EXTENSION postgis_topology;
SET search_path = topology,public;

I import my layer with QGIS

SELECT topology.CreateTopology('ec_topo', 27572);
SELECT 
topology.AddTopoGeometryColumn('ec_topo','public','ec','topo_geom','POLYGON');

DO $$DECLARE r record;
BEGIN
  FOR r IN SELECT * FROM ec LOOP
    BEGIN
    SELECT 
topology.TopoGeo_AddPolygon('ec_topo',st_geometryn(r.geom,1),1);
    EXCEPTION
      WHEN OTHERS THEN
        RAISE WARNING 'Loading of record % failed: %', r.id, SQLERRM;
    END;
  END LOOP;
END$$;

I have :
ATTENTION:  Loading of record 1 failed: la requête n'a pas de 
destination pour les données résultantes

I don't know where I'm wrong

If you have an idea

Thanks

Regards

Ludovic

PS : (si j'avais sur que c'était toi qui répondrait, j'aurai écrit 
sur nos forums francophone ;-) )

Le 15/01/2014 08:25, Christophe Vergon a écrit :
Hello, (bonjour)

When you udpdate a topology by using a SET statement if a polygon 
intersect an other you will have this error.
If you want to create a topology from polygons try to use the 
topogeo_addpolygon function, the intersection between two polygons 
will be a new face.

If, as I mean, you use a french survey "cadastre" data set, it's the 
best way to do that.



Ludovic Granjon a écrit :
Hi all

I try to import a polygon layer to postgis and build topology with 
tolerance.
I try something like that

SELECT CreateTopology('ec_topo2', 27572);
SELECT AddTopoGeometryColumn('ec_topo2', 'public', 'ec', 
'topogeom2', 'MULTIPOLYGON');
UPDATE ec SET topogeom2 = toTopoGeom(geom, 'ec_topo', 1, 1.0);

But when I do that, I have

********** Erreur **********

ERREUR: Spatial exception - geometry intersects edge 262
État SQL :P0001
Contexte : fonction PL/pgsql « topogeo_addlinestring », ligne 124 à 
affectation
SQL statement "SELECT array_cat(edges, array_agg(x)) FROM ( select 
topology.TopoGeo_addLinestring(atopology, rec.geom, tol) as x ) as 
foo"
fonction PL/pgsql « topogeo_addpolygon », ligne 24 à affectation
fonction PL/pgsql « totopogeom », ligne 112 à FOR sur des lignes de 
SELECT
fonction PL/pgsql « totopogeom », ligne 94 à affectation

I try to modify the tolerance parameter but it still doesn't work

Have  you a solution for that ?

Thanks a lot

Regards

Ludovic



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