[Qgis-user] repairing geometry

[William Kyngesburye]

Forgot to say: QGIS 1.7 trunk.

I also tried a union of the polygon and an adjacent one directly in postgis.  Invalid geometry.

On Mar 29, 2011, at 8:55 AM, William Kyngesburye wrote:

> I'm a bit stumped on this.  I have some polygons in a postgis layer with spikes into the interior.  The spikes are an exact retrace going into and back out (the digitizers never completed the line to another edge of the polygon to split it into 2 polygons).  The node edit tool shows many, but not always all, nodes along the spike with problems, I think it depends on how many other node errors are on other parts of the polygon.  They exist in the layer fine, but I can't do any geometry operations like merge or split (nothing happens), though I can move/add/delete vertices.  I need to extend the "spike" to split the polygon.
> 
> <Screen shot 2011-03-29 at 8.39.21 AM.png><Screen shot 2011-03-29 at 8.52.53 AM.png>
> 
> I tried exporting to a line shapefile (Vector->Polygons to Lines), where a split will will work to separate the spike from the outer ring, then I extend the line and eventually create 2 polygons, which I can copy-n-paste back to the original polygon layer, but I ran into invalid geometry types:
> 
> http://trac.osgeo.org/qgis/ticket/3604
> 
> Any other ideas?  I don't want to retrace the whole spike, as some are very long.  Or is this a bug in handling invalid geometry?
> 
> -----
> William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
> http://www.kyngchaos.com/
> 
> All generalizations are dangerous, even this one.
> 
> 
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-----
William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
http://www.kyngchaos.com/

"I ache, therefore I am.  Or in my case - I am, therefore I ache."

- Marvin