[Qgis-user] GEOPROCESSING: UNION of more polygons of different layers

[Azzurra Lentini]

Dear all,
thanks a lot.
Yes is it true: I need to copy the content of one layer into the other, so
I need Merge.
Anyway thanks for the useful advices also regarding the union.

bye bye
Azzurra

2015-12-21 14:45 GMT+01:00 Andreas Neumann <a.neumann at carto.net>:

> Hi Matthias,
>
> Thanks for this useful hint.
>
> But this "union" is also just a concatenating - it is in the sense of a
> union of SQL result sets. It does not create new geometries, as a geometric
> union would do.
>
> So the question remains: what type of "union" does Azzurra want? a
> concatenation of several data sets or a geometric union where new
> geometries of overlapping features are generated?
>
> Andreas
>
>
> On 21.12.2015 14:10, Matthias Kuhn wrote:
>
>> I have recently used OGR VRT for this:
>>
>> http://www.gdal.org/drv_vrt.html
>> *OGRVRTUnionLayer*
>>
>> If you are not afraid of editing an XML file, that would be an approach.
>>
>> Matthias
>>
>>
>> On 12/21/2015 01:37 PM, Andreas Neumann wrote:
>>
>>> Hi,
>>>
>>> Isnt' merge something else than union? As far as I know, merge only
>>> copies the content of one layer into the other, whereas union really
>>> unites overlapping geometry and creates new features. You'd have to
>>> define how it handles the attributes.
>>>
>>> Andreas
>>>
>>> On 21.12.2015 11:49, Lewis Villierme wrote:
>>>
>>>> Hi,
>>>>
>>>> There's a tool called in vector/Data management/Merges Multiples
>>>> layer to one
>>>>
>>>> you can specify a folder in which you have all your shapefile to merge.
>>>>
>>>> regards.
>>>>
>>>> 2015-12-21 10:04 GMT+00:00 Azzurra Lentini <azzurralentini at gmail.com>:
>>>>
>>>>> Dear all,
>>>>> is it possible in Qgis to do the union of more polygons of
>>>>> differents layers
>>>>> (so from more input layers to have one output layer as I can do in
>>>>> arcgis)?
>>>>>
>>>>> In vector --> geoprocess --> union
>>>>> is the union of only 2 different layers but is not possible a union
>>>>> a more
>>>>> of 2 layers.
>>>>>
>>>>> Thanks, Azzurra
>>>>>
>>>>> --
>>>>> Dr. Hydrogeologist
>>>>> AZZURRA LENTINI
>>>>> Expert of evaluation environmental hazards
>>>>> GIS application
>>>>> Haity Mobile Tel: 0050946057393
>>>>> ++++++++++++++++++++++++++
>>>>> Italy Mobile Tel.: **(39) 338 24 40 676
>>>>> ++++++++++++++++++++++++++
>>>>> SKYPE azzurrahydro
>>>>> ++++++++++++++++++++++++++
>>>>> azzurralentini at gmail.com
>>>>> ++++++++++++++++++++++++++
>>>>> *Par respect pour l'environnement,*
>>>>>
>>>>> *n'imprimez ce mail qu'en cas d'absolue nécessité*
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
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-- 
Dr. Hydrogeologist
AZZURRA LENTINI
Expert of evaluation environmental hazards
GIS application
Haity Mobile Tel: 0050946057393
++++++++++++++++++++++++++
Italy Mobile Tel.: **(39) 338 24 40 676
++++++++++++++++++++++++++
SKYPE azzurrahydro
++++++++++++++++++++++++++
azzurralentini at gmail.com
++++++++++++++++++++++++++
*Par respect pour l'environnement,*

*n'imprimez ce mail qu'en cas d'absolue nécessité*
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