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I have a raster layer (DTM of central Scotland) and a vector layer that shows the location of archaeological sites. I want to know how to join the layers so that I can figure out what height each archaeological site is at.

I have tried converting the raster layer into a vector layer and then doing a spatial joint but that does not seem to be working since when I polygonise the layer I seem to lose information.

Does anyone know how to "ask" QGIS what sites fall within what height or how to join a raster and a vector layer?

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I am not sure if it really solves your issue, but I just read in another post about Zonal Statistics. Might that help? https://docs.qgis.org/2.18/en/docs/user_manual/plugins/plugins_zonal_statistics.html

Otherwise maybe the point sampling tool might help you. There you can extract the values in a point-grid of the raster file. And afterwards you could join the two polygones maybe? http://www.digital-geography.com/qgis-plugins-point-sampling-tool/

Good luck with it :)

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In case your archeological data are points, you might able to use v.what.rast.points from the GRASS processing toolbox.

The first thing is to have a field in the location vector to sotre the elevation data.

In my example I have a layer caled ponts and I add a field called z (a double with 3 decimals)

enter image description here

Then use the GRASS command v.what.rast.points as in the picture below. When I tried I had some trobles with the whereargument, but then I just put a 1 state it is always true.

I left the parameter Sampled empty, so a new temporary layer was created. You could also overwrite the vector file with points, but it is a bit risky to try tools for the very first time with your data, better the long way.

enter image description here

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