[Qgis-user] Trouble with overlay in 1.8.0

[Havard Tveite]

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/