[postgis-users] The "bow tie" error

[Stephen Woodbridge]

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.

-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
>
> hugues.francois at irstea.fr
>
>
>
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