Re: [Qgis-user] Vacuuming a vector polygon layer with a point layer in QGIS 2.8.2 (windows)

Julie Houge Hansen Mon, 06 Jul 2015 04:55:14 -0700

Hi Kristian

I was hoping I would be able to find a more automatic way of doing this as I 
have to do it many times... Maybe I have found a solution using the GRASS 
module r.cost.

Thank you for your help!

Med venlig hilsen

Julie Houge Hansen
PhD Student, Inst. of Chemical Eng., Biotechnology and Environmental Tech.

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Fra: qgis-user-boun...@lists.osgeo.org
[mailto:qgis-user-boun...@lists.osgeo.org] På vegne af Kristian Evers
Sendt: 3. juli 2015 14:46
Til: qgis-user@lists.osgeo.org
Emne: Re: [Qgis-user] Vacuuming a vector polygon layer with a point layer in
QGIS 2.8.2 (windows)

Hi Julie.

You need to define a surrounding area for each of the biogas plants. I suggest
you base the surrounding areas on the polygons you already have, so that each
plant has a polygon that is a union of several surrounding biogas-potential
polygons. How to do this is up to you.
Hereafter you can select all potential-polygons that intersect the
plant-polygons and sum up the potentials within each of the plant-polygons.

I hope that was enough to bring you on the right track.

Kristian

Fra:
qgis-user-boun...@lists.osgeo.org<mailto:qgis-user-boun...@lists.osgeo.org>
[mailto:qgis-user-boun...@lists.osgeo.org] På vegne af Julie Houge Hansen
Sendt: fredag 03. juli 2015 13:35
Til: qgis-user@lists.osgeo.org<mailto:qgis-user@lists.osgeo.org>
Emne: [Qgis-user] Vacuuming a vector polygon layer with a point layer in QGIS
2.8.2 (windows)

Dear all

I have tried asking my local QGIS expert but unfortunately she is for once not
able to help me. I hope someone can.

- I have a vector polygon layer that contains data for the amount of
biogas potentially available in a polygon - unit is m3/ha/year. The polygons
are of varying size.

- I have another vector point layer with data for the amount of biogas
already produced on specific biogas plants - unit in m3/year.

- I would like to combine the two layers so that I "vacuum" the area
surrounding the biogas plants for biogas potential. This will reveal where
there are still areas with sufficient biomass available for a new biogas plant
to be build.

I have no clue how to do this calculation but I think it should be possible.
Can anyone help me out?

The overview I have of my data now looks like this:
[cid:image002.jpg@01D0B7F3.339FA1E0]

The size of the shown point data is independent on the polygon layer. I would
like it to be dependent on the biogas potential available (in the polygon
layer). I would like the size of the points to reflect how far you would have
to drive (radius to the biogas plant) in order to get all the biomass needed to
produce the biogas you intend to.

I am using QGIS version 2.8.2 64 bit with Windows.

Best regards