[Qgis-user] Invalid geometry

[Ramon Andiñach]

Hi,

As a start, the c1.shp file in the attached zip has no projection details. It has projection files, but they're empty, so QGIS will either assume a projection or ask, depending on what setting you've used. This will also cause problems later.

I'm not what you're expecting out of an intersect between a point layer and a polygon layer. QGIS is going to get confused somewhere as it needs 3 points to make a polygon, and in effect you're asking it to make a polygon of one point. (Which is why you're being warned about the geometry error). It will still make a file, but it might not be what you want.

Looking at the results I'd guess Sextante is just not telling you about this. They look very similar to me.

You could make a (very small buffer) around the points and then work with that...

Could you explain what you're expecting QGIS to do?

-ramon.
(Who knows a little, but suspecting not enough)

On 22/06/2012, at 22:37 , Sergio A Estay wrote:

> Hi Everybody and Ramon,
> 
> From the last actualization from QGIS 1.7.4 to 1.8.0 all my shp files have "invalid geometry". For that reason now I can't make intersection between vector layers. Previous to the actualization everything works fine (using the same vector files).
> 
> As a polygons shp files I use this cover:
> 
> http://www.mappinghacks.com/data/TM_WORLD_BORDERS_SIMPL-0.2.zip
> 
> As a points vector layer I use the attached shp file.
> 
> If I try to make the intersection from Qgis/vectorial/geoprocess menu I obtain "invalid geometry", but If I install the sextante python complement, open the Toolbox and run intersection from the ftools submenu everything is OK.
> 
> Any advice will be very useful
> 
> Thanks
> 
> Sergio
> 
> -- 
> Sergio A. Estay
> Inst. Ciencias Ambientales y Evolutivas
> Universidad Austral de Chile
> Casilla 567, Valdivia, Chile
> Phone: 5663-293913
> http://www.ciencias.uach.cl/instituto/ciencias_ambientales_evolutivas/academicos/sergio-estay.php
> 
> <P1.zip>