[Qgis-user] Trouble with overlay in 1.8.0

[Havard Tveite]

I have done some more testing and searching.

For very simple datasets, it seems that most overlay
operations work.  The exception is for point datasets.
I found Bug #5861 (Vector menu and Sextante -> ftools
behaving inconsistently) that seems related.

However, with some more complex datasets, I get problems
with some line-polygon intersects and polygon-polygon
unions.

Håvard

On 8/29/2012 10:39 AM, Havard Tveite wrote:
> After moving to QGIS version 1.8.0 (from 1.7.4), I am having
> trouble with overlay (intersection, union).
> The intersect function (Vector-> Geoprocessing Tools-> Intersect)
> gives the following warning:
>
> * Warnings:
> * Feature geometry error: One or more output features ignored due to invalid geometry.
> * Some output geometries may be missing or invalid.
>
> The resulting dataset contains no elements (but has all
> the attributes from the datasets used in the operation).
> I have tested with some "normal" and some very simple datasets
> (point dataset with one point and a polygon dataset with one
> polygon), and observe the same behaviour for all the cases.
> I have only tested with Shapefile datasets.
>
> I have done most of the testing on Windows XP, but also some
> testing on Ubuntu 12.04.
>
> union seems to have the same problems as intersection.
>
> I had no problems with intersection in 1.7.4.
>
>
> Håvard Tveite

-- 
Håvard Tveite
Department of Mathematical Sciences and Technology, UMB
Drøbakveien 31, POBox 5003, N-1432 Ås, NORWAY
Phone: +47 64965483 Fax: +47 64965401 http://www.umb.no/imt/