Thanks for your suggestion and your advices to post on qgis list. Il will do it as soon as possible.
Hugues. -------- Message d'origine-------- De: [email protected] de la part de Stephen Woodbridge Date: ven. 22/03/2013 19:15 À: [email protected] Objet : Re: [postgis-users] The "bow tie" error On 3/22/2013 1:53 PM, Hugues François wrote: > Hello, > > Thanks for your answer Stephen. Of course dumping the multipolygons > works well with qgis. But for our users we need to keep the unique id > attached to each object, simple or multipolygon. They might need to > export data to their gis software for their work and all our database > is built based on this uniqueness constraint . Well it is an attempt to work around a problem that is not related to postgis. Another alternative might be to require your users to explode multipolygons before getting to this point so the new records all have a unique id. > In fact, I really don't understand why qgis see these as an error. > they seem topologically correct to me, especially since unioning the > dumped part in qgis create the same error ! Definitely, it sounds > like the error comes from qgis and the error seems impossible to > solve. Right, if the bug is in qgis, then you can not expect postgis to fix it. Sounds like you need to raise this as a bug on the qgis list and ask them when you can expect a fix. For simplicity in conveying the problem leave postgis out of it, as you can reproduce the problem without postgis being involved. -Steve W > Hugues. > > -----Message d'origine----- De : > [email protected] > [mailto:[email protected]] De la part de Stephen > Woodbridge Envoyé : jeudi 21 mars 2013 22:11 À : > [email protected] Objet : Re: [postgis-users] The "bow > tie" error > > On 3/21/2013 5:06 PM, Stephen Woodbridge wrote: >> Francois, >> >> Can you dump the polygons in the multiplyogon and create separate >> records for them. So in you example graphic, you would end up with >> two separate polygons the touch at a point. I think this would be >> OK for qgis. > > This might be helpful: > > http://www.bostongis.com/postgis_dump.snippet > http://postgis.17.n6.nabble.com/converting-multipolygon-to-polygon-td3530291.html > > >> -Steve W >> >> On 3/21/2013 4:57 PM, Francois Hugues wrote: >>> Hello, >>> >>> I have to deal with a dataset with a lot of errors. I ran a >>> st_makevalid which seems to give me good results (all polygons >>> then appear to be valid, closed and simple). But, when I open >>> this table as a layer in qgis it still throws me a lot of errors. >>> The image attached to this message provide you with an example >>> and the error said : Le segment 0 de l'anneau 16 du polygone 6 >>> est intersecté au segment 0 de l'anneau 1 du polygone 7 à >>> 933828.8196, 6261164.472 (in english this may be something like : >>> line 0 of ring 16 is intersected by line 0 of ring 1 of polygon 7 >>> at point...). >>> >>> As the rings of the multipolygon share one point, I tried to dump >>> it and then to union the rings to build a single polygon but I >>> got a multipolygon back and still an error. >>> >>> The dataset have a lot of "bow ties" and it seems that >>> st_makevalid change them to multipolygon but that do not correct >>> all errors in qgis. >>> >>> Does anyone have an idea to find any solution ? >>> >>> Hugues >>> >>> -- >>> >>> >>> >>> Hugues FRANÇOIS >>> >>> [email protected] >>> >>> >>> >>> _______________________________________________ postgis-users >>> mailing list [email protected] >>> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >>> >> >> _______________________________________________ postgis-users >> mailing list [email protected] >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > > _______________________________________________ postgis-users mailing > list [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing > list [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
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