"Check Geometry Validity" produces incorrect result

[qgib]

Author Name: Daniel Baston (@dbaston)
Original Redmine Issue: 12730
Affected QGIS version: 2.8.1

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The following is a valid, two-part MULTIPOLYGON:

MULTIPOLYGON (((-71.757875 44.565735, -71.748526 44.560716, -71.758014 44.564355, -71.757875 44.565735)),
((-71.760777 44.567292, -71.75725 44.56739, -71.757875 44.565735, -71.760777 44.567292)))

The "Check Geometry Validity" tool reports the following:

1,segment 0 of ring 0 of polygon 0 intersects segment 0 of ring 1 of polygon 1 at -71.757875, 44.565735
1,Geometry has 1 errors.

Using build 2863f20

[qgib]

Author Name: Arnaud Morvan (@arnaud-morvan)

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The two parts of the polygon have one point in common.
In Settings/Options/Digitizing/Feature creation, there is two options for validity checking which are QGIS or GEOS.
When checking the validity from ftools menu entry,
QGIS method effectively returns that the poligon is not valid:
1,segment 0 of ring 0 of polygon 0 intersects segment 0 of ring 1 of polygon 1 at -71.757875, 44.565735
1,Geometry has 1 errors.
GEOS method returns that the polygon is valid.

[qgib]

Author Name: Giovanni Manghi (@gioman)

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Arnaud Morvan wrote:

GEOS method returns that the polygon is valid.

shoud we close this then?

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• status_id was changed from Open to Feedback
• category_id was configured as 44

[qgib]

Author Name: Daniel Baston (@dbaston)

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That's interesting. Is the intent of the "QGIS Method" to validate against a different set of rules than GEOS / OGC?

[qgib]

Author Name: Daniel Baston (@dbaston)

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Related to qgis/QGIS-Documentation#472

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• assigned_to_id was configured as Jürgen Fischer

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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• category_id removed 44
• assigned_to_id removed Jürgen Fischer

[qgib]

Author Name: Jürgen Fischer (@jef-n)

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Fixed in changeset "3eef29ab1bd4cc007b7db5012dad23d9c39e2249".

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• status_id was changed from Feedback to Closed