[Qgis-user] Overlapping

[Germán Carrillo]

Hi Michael,

In line with Harrissou's advice, yesterday I tweeted [1] about an extension
to the "Overlap analysis" in QGIS, which works on exactly 2 layers and is
called "Overlap analysis by class".

The outputs are both overlap area and percentage per class. Perhaps it
could help you.

See installation instructions at [2].

Regards,

Germán
-----------
[1] https://twitter.com/GeoTux2/status/1491684612086636547
[2] https://github.com/gacarrillor/QGIS-Resources/#installation


El vie, 11 feb 2022 a las 15:49, Harrissou s. (<delazj at gmail.com>) escribió:

> Hi,
> A starting point can also be the Processing "overlaps analysis" algorithm
> [0] (sorry I don't know how the output actually looks like) followed by
> some aggregate analysis.
>
> [0]
> https://docs.qgis.org/testing/en/docs/user_manual/processing_algs/qgis/vectoranalysis.html#overlap-analysis
>
> Regards,
> Harrissou
>
> Le 11 février 2022 17:58:00 GMT+01:00, chris hermansen <
> clhermansen at gmail.com> a écrit :
>>
>> Michael and list
>>
>> On Fri, Feb 11, 2022 at 8:49 AM Michael Williamson <
>> michael at michaelandjane.org.uk> wrote:
>>
>>> I am sure this is easy but I can’t work out which facility to use
>>>
>>>
>>>
>>> I have two layers. Layer A is made up of some large polygons while Layer
>>> B is made up of smaller polygons. The Polygons in Layer A overlap one or
>>> more of the polygons in layer B. In most cases the overlap is 100% but
>>> there are a few cases where the overlap is less than that.
>>>
>>>
>>>
>>> Layer B contains population and other data as numerical attributes and I
>>> want to populate corresponding attributes in layer A with the weighted
>>> total of the attributes in layer B depending on the amount of overlap.
>>>
>>>
>>>
>>> I have found various tools but I cannot work out which one to use. The
>>> ones I have found seem to do part of the job but not all of it.
>>>
>>>
>>>
>>>
>>> Probably you want
>>
>> Vector > Geoprocessing Tools > Intersection
>>
>> That will give you a new layer C with the geometric intersections of your
>> Layer A and Layer B.  The attribute table for Layer C will contain the
>> attributes of both A and B.
>>
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