[Qgis-user] How to use the digitize tab in layer properties in QGIS 3.4

[Simon Haufe]

Dear QGIS-Users,

currently I am confused how to use the digitize tab in the layer
properties. What is behind to check if a geometrie is valid or the
topology has gaps, missing vertexes or is overlapping? The professional
context I know pretty well. But what are the next steps in QGIS itself
to show all the checking possibilities?

Background: QGIS 3.4 on Linux Ubuntu 18.04.

Thanks for all your answers.

Best regards
Simon Haufe
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http://changelog.qgis.org/en/qgis/version/3.4-LTR/#geometry-precision
http://changelog.qgis.org/en/qgis/version/3.4-LTR/#automatically-remove-duplicate-nodes
http://changelog.qgis.org/en/qgis/version/3.4-LTR/#check-for-geometry-validity
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Christophe Damour - SIGéal

Post by Simon Haufe
Dear QGIS-Users,
currently I am confused how to use the digitize tab in the layer
properties. What is behind to check if a geometrie is valid or the
topology has gaps, missing vertexes or is overlapping? The
professional context I know pretty well. But what are the next steps
in QGIS itself to show all the checking possibilities?
Background: QGIS 3.4 on Linux Ubuntu 18.04.
Thanks for all your answers.
Best regards
Simon Haufe

[Andreas Wicht]

Hi,

Post by Simon Haufe
currently I am confused how to use the digitize tab in the layer
properties.

I am experiencing the same confusion. Setting the desired parameters is trivial
but I am also missing the panel shown in the gif where errors are displayed.
Hope anybody can shine a light on this.

Best regards
Andreas

[B***@stadt.wolfsburg.de]

Hi,
it depends on the QGIS version you are using :-). In 3.4.0 you have to make the settings for the desired topology check, save and close the project. After reopening, the function is available. The check, however, only takes place after the digitization of the geometry element when saving. If an error is found, the panel "Geometry Validation" appears on the right. In 3.4.1 the error is fixed and no saving, closing and reopening of the project is necessary anymore.

Hope this helps.

Regards
Burghardt

-----Ursprüngliche Nachricht-----
Andreas Wicht
Gesendet: Dienstag, 6. November 2018 09:15
Betreff: Re: [Qgis-user] How to use the digitize tab in layer properties in QGIS
3.4
Hi,

Post by Simon Haufe
currently I am confused how to use the digitize tab in the layer
properties.

I am experiencing the same confusion. Setting the desired parameters is trivial
but I am also missing the panel shown in the gif where errors are displayed.
Hope anybody can shine a light on this.
Best regards
Andreas
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[Andreas Wicht]

* Precision and remove duplicate nodes should work straightforward.
* The panel will show up immediately when there are errors on invalid geometries (e.g. self-intersection).
* The panel will show up when trying to save the layer when topology checks fail.
With the initial release there was an issue that the checks were only enabled if the project was saved and reloaded. Meanwhile this has been fixed and the checks can be activated and will take effect immediately (with the next patch release 3.4.2 or any nightly build until then). There were also some severe issues which caused QGIS to crash which are already fixed in 3.4.1.

Thank you for your response, Matthias. I followed the instructions
(using 3.4.1) and got it to work.
I just noticed, that I am only able to force missing vertex errors.
When deliberately constructing gaps or overlaps those will not be
detected or QGIS crashes while checking the layers' topology. This
happened using a geopackage containing just 3 very simple polygons.
Would that be one of the issues being fixed by the upcoming 3.4.2
release?

Cheers
Andreas

[Andreas Wicht]

Hi again,

With the initial release there was an issue that the checks were only enabled if the project was saved and reloaded. Meanwhile this has been fixed and the checks can be activated and will take effect immediately (with the next patch release 3.4.2 or any nightly build until then).

After upgrading my installation to 3.4.2 (Win10) I tried the feature
again and run into the following problem:
I have a layer open (tested with *.shp *.gpkg and PostGIS), set the
desired digitizing setting in the layer-options and forcefully add a
topological error.
What then happens is that the validation finds the error, therefore
the layer can not be saved, but the panel does not open.
The log messages say:
- 2018-12-03T11:06:33 INFO Geometry Validation : Running
geometry validation checks before saving…
- 2018-12-03T11:06:37 WARNING Could not save changes. Geometry
validation failed.

Am I missing any prerequisite which is necessary? I tested on fresh
layers/projects.

Cheers