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I have a map with huge amount of points (9562 villages) and two rasters: population density and land elevation.

I am trying, without success for the moment, to select just those villages with high population density and low land elevation.

Does anyone have the solution?

I tried to do it using a site suitability analysis, but for that I need the v.kernel GRASS command which is not working on my pc (another problem described here: v.kernel is missing under Processing Toolbox GRASS GIS 7 commands).

ahmadhanb
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Janita
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1 Answers1

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You can extract raster values of population density and land elevation to village point shapefile using Plugin: Point sampling tool which can be downloaded from plugin manager in QGIS.

The tool works perfectly if the projection of the raster(s) data and the point shapefile are same. Working with different projections for the raster(s) and shapefile data will create a shapefile with empty columns of raster values.

After assigning the population density and land elevation to the village points, you can select those points with high population density and located in low land area.

ahmadhanb
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  • Thanx for your reply. What do you mean by "projection"? – Janita Jun 12 '16 at 12:03
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    I mean if the point shapefile in WGS84 and the raster data in UTM Projection, the raster information will not be assigned to the point shapefile. You will get new point shapefile with empty fields. – ahmadhanb Jun 12 '16 at 14:00
  • I have a problem with the plugin. It seems that it's not included in the plugins that I can install, see the description of the problem here: http://gis.stackexchange.com/questions/198111/plugin-not-available-point-sampling-tool. Do you have any idea how to solve the problem? – Janita Jun 13 '16 at 08:10
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    Are you behind a proxy? – ahmadhanb Jun 13 '16 at 08:15
  • Stupid question: how can I know that? – Janita Jun 13 '16 at 08:19
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    Go to Settings -> Options -> Network. Take a screenshot and update your question to include that image. May be someone can help you? – ahmadhanb Jun 13 '16 at 08:26
  • I just updated the question: http://gis.stackexchange.com/questions/198111/plugin-not-available-point-sampling-tool – Janita Jun 13 '16 at 09:01
  • Finally I found the solution (thank you @Joseph) so I used the Point sampling tool plugin correctly and it works perfectly. Now I have a new layer with two columns: pop density and elevation that described all the villages. Ill do then a selection by exppression to find those with high pop density and low elevation. Many thanx for your help. – Janita Jun 13 '16 at 12:18