[Qgis-user] Fix Geometries

[GILLEN Finbar]

Thanks for all the responses on this... I am going to try the Check Validity plugin ('QGIS' method) as a starter within QGIS 3.2. I am using a fairly detailed flood polygon so accuracy is key. I will let you know how I get on.

Thanks again,
Finbar

-----Original Message-----
From: Qgis-user <qgis-user-bounces at lists.osgeo.org> On Behalf Of Nicolas Cadieux
Sent: 21 May 2019 23:02
To: qgis-user at lists.osgeo.org
Subject: Re: [Qgis-user] Fix Geometries

Hi,

The Geometry Checker plugin will add a the 'Check Geometries' option in the vector menu.  It is very unstable with the current version of QGIS. If you get it to run, it should solve most problems.  I get it to run when I only select one test at a time.

The most predictable tool is the vector/geometry tools/Check validity using the 'QGIS' Method (not GEOS).  That should fix your file.  There is a 'remove duplicate vertices' and 'delete duplicate geometries' in processing.  Your problem could also be caused by a module not working with multipart objects.  Go to vector/Geometry tools/Multiparts to singleparts.

If your lines don't touch,   try the 'snap Geometries to layer ' in processing.

Nicolas

On 2019-05-21 2:54 a.m., Mithoefer wrote:
> Hi Finnbar,
>
> What plugin are you talking about and what QGIS version do you use?
> You have a number of tools to check geometries. Try "Topology checker" 
> or "Geometry checker" to see where the problems are (invalid 
> geometries). Geometry checker is also able to fix some issues. Maybe 
> thats the one you use.
>
> Anotehr option is GRASS GIS. Have you ever worked wit GRASS GIS? You 
> can create a GRASS database and import your polygons. GRASS GIS uses a 
> topolgical data model and is quite powerful in establishing a desent 
> data model with snapping options and clean functions. You can also try 
> GRASS tools from the processing framework like build polygons or clean.
>
> Regards
> Klaus
>
> Am 20.05.19 um 11:31 schrieb GILLEN Finbar:
>> Hi All,
>>
>> I have a few polygon layers where anytime I go to use them I have to 
>> use the fix geometries plugin so that invalid geometries are fixed.
>>
>> When I save the output from the fixed geometries plugin and add it in 
>> a new project the same issues appears where I can’t use it accurately 
>> to do a Select or Join by Location because some of the geometries are 
>> still seen as invalid even though they have been ‘fixed’.
>>
>> Is there anyway solution to this or do I have to keep using the fix 
>> geometries plugin anytime I use the polygons for analysis?
>>
>> Regards
>>
>> Finbar
>>
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Unless stated to the contrary, any opinions expressed in this message are personal and may not be attributed to AXA Insurance dac or any member of the AXA Group of Companies.

AXA Insurance dac is regulated by the Central Bank of Ireland. For business in Northern Ireland, AXA Insurance dac is authorised by the Central Bank of Ireland and subject to limited regulation by the Financial Conduct Authority. Details about the extent of our regulation by the Financial Conduct Authority are available from us on request. AXA Insurance dac is a private company limited by shares, registered in Ireland number 136155. Registered Office Wolfe Tone House, Wolfe Tone Street, Dublin 1.

"AXA Supporting Road Safety in Ireland"

Internet e-mails are not necessarily secure. AXA Group does not accept responsibility for changes made to this message after it was sent. To help promote the use of electronic documents and to be kinder to the environment, please consider whether you really need to print this
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