qgis doesn't show any message/warning when splitting a polygon with an invalid geometry

[qgib]

Author Name: xr6ute - (xr6ute -)
Original Redmine Issue: 2829

Redmine category:digitising
Assignee: nobody -

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While editing a shape file, trying to split the feature has no affect. Trying to split the same shape file with v1.2.0 used to cause a crash.
Creating a new ring and splitting that does work as expected.

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• WEIR.zip (xr6ute -)
• Screenshot.png (Giovanni Manghi)

[qgib]

Author Name: Paolo Cavallini (@pcav)

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Confirmed. In my case, it crashes with:

Error:

GDAL Error 1: [[TopologyException]]: found non-noded intersection between LINESTRING (138.783 -34.5531, 138.783 -34.5531) and LINESTRING (138.783 -34.5531, 138.783 -34.5531) at 138.783 -34.5531

Segmentation fault

[qgib]

Author Name: Giovanni Manghi (@gioman)

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see attached image. The geometry does not seems correct. Fix it and the tool will work fine.

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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Replying to [comment:2 pcav]:

Confirmed. In my case, it crashes with:

No crash here.

Error:

GDAL Error 1: [[TopologyException]]: found non-noded intersection between LINESTRING (138.783 -34.5531, 138.783 -34.5531) and LINESTRING (138.783 -34.5531, 138.783 -34.5531) at 138.783 -34.5531

GDAL? Strange. There should be a GEOS exception, if any. Although the rest of the message looks like one. Doesn't this only crash with some plugins involved?

[qgib]

Author Name: Paolo Cavallini (@pcav)

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So we got another problem now: I suspected the layer was invalid, so I checked with fTools, which it couldn't find the error.
Two issues then:

• QGIS shouldn't crash in case of editing invalid geometries, and it should report a meaningful error when trying to manipulate them

• incorrect geometries should be found by fTools (probably better opening a ticket on this)

[qgib]

Author Name: Paolo Cavallini (@pcav)

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Right: uninstalling SDA4PP plugin removes the crash. A meaningful erro message would be good to have anyway.

[qgib]

Author Name: xr6ute - (xr6ute -)

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Sorry about the bad geometry file I hadn't noticed that, and I can confirm Lutra is correct, once I fixed the geometry the tool worked as expected.
Thanks for looking in to this, the response is exceptional, inline with the overall QGIS experience :-).

[qgib]

Author Name: Giovanni Manghi (@gioman)

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New description:

See attached polygon shapefile. It has an invalid geometry and if you try to split it qgis does nothing. It should throw a message/warning.

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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fixed in f33d9f2 (SVN r15813).

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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• resolution was configured as fixed
• status_id was changed from Open to Closed