[Qgis-developer] Make valid in master

Larry Shaffer larrys at dakotacarto.com
Thu Jan 16 00:11:14 PST 2014


Hi Andrea,

On Thu, Jan 16, 2014 at 12:39 AM, Andrea Peri <aperi2007 at gmail.com> wrote:

> It should be applied only when the test IsValid fail.
> This should limit the slowness.
> Also pay attention that something the result of a MakeValid on an Invalid
> poligon could be a MultiPolygon or also a Collection.
> So to use it in an automatic manner need to apply also a
> ST_Multi(CollectionExtract(ST_MakeValid(geometry),3)).
> To be sure that it is always a geometry of the same kind.
>

Thank you. I was wondering how to do that!

I suppose that would be for the QgsGeometry class function(s) to handle,
thereby just returning an array of same geom type passed in, or returning
whether the fix was actually done and assigning any results to a referenced
variable.

Regards,

Larry



> A.
>
>
>
>
> 2014/1/16 Larry Shaffer <larrys at dakotacarto.com>
>
>> Hi Paolo,
>>
>>
>> On Wed, Jan 15, 2014 at 11:35 PM, Paolo Cavallini <cavallini at faunalia.it>wrote:
>>
>>> Hi all.
>>> To the best of my knowledge, our make clean command, available through
>>> the Processing subplugin:
>>>
>>> http://plugins.qgis.org/plugins/processinglwgeomprovider/
>>>
>>> is the most effective method to clean up invalid geometries.
>>> I would therefore suggest to include it in master, in order to have it
>>> available straight away for everybody.
>>> This depends on lwgeom, available at least on Debian and Windows.
>>>
>>
>> I have recently made a Homebrew formula for Mac that allows liblwgeom to
>> be built without Postgres/PostGIS installs (a bit of a hack, actually). So,
>> the standalone lib is now readily available on Mac OS X as well [0].
>>
>> +1 for this to be included in QgsGeometry or similar class.
>>
>> It would help solve labeling issues where the extents-clipped geometry is
>> invalid. Would slow rendering down, of course, but would be good to have as
>> an option for faster machines and print jobs. Note: the validity fix would
>> be applied to the duplicates of feature geometries, which are used by PAL.
>>
>> [0]
>> https://github.com/Homebrew/homebrew/blob/master/Library/Formula/liblwgeom.rb
>>
>> Larry
>>
>>
>>
>>
>>> Opinions? Any blockers?
>>>
>>> All the best.
>>> --
>>> Paolo Cavallini - www.faunalia.eu
>>> QGIS & PostGIS courses: http://www.faunalia.eu/training.html
>>> _______________________________________________
>>> Qgis-developer mailing list
>>> Qgis-developer at lists.osgeo.org
>>> http://lists.osgeo.org/mailman/listinfo/qgis-developer
>>>
>>
>>
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>
>
>
> --
> -----------------
> Andrea Peri
> . . . . . . . . .
> qwerty àèìòù
> -----------------
>
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