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I have a polygon that is my region of interest. I also have a database of observation points that I have imported into QGIS as a points layer. I'd like to exclude all the observation points that fall outside my region of interest (the polygon). Also happy to delete those within the polygon if that is easier (I have polygons of both region of interest and region not of interest if that makes sense). Ultimately I'm just wanting to identify those within the region and export that information (at least for now).

I can do this manually by deleting each point, but is there an automated way I can do this in QGIS?

I'm afraid I haven't managed to find anything to really try, what I've found relates to clipping rasters or polygons, not points. Any suggestions much appreciated - thanks

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A very simple approach is to just clip the points layer with the polygon layer (giving a new layer with just the points which lie within the polygon).

go Vector->Geoprocessing Tools->Clip.

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This is the answer i would give to this question. Except maybe to add that if it is one polygon on a multi-polygon layer to select the polygon in question and save it as a seperate layer, then use your clip function. –  Gerald Sep 12 '13 at 8:40
    
Thanks MappaGnosis and Gerald - this is exactly what I was looking for. –  user20235 Sep 13 '13 at 0:15
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You can use "Vector->Research tools-> Select by location" to select all the points intersecting with your "region not of interest" polygon.

You first have to select your polygon. Then you use the "select by location" tool, specifying the point layer and the polygon layer. Then when the points are selected you can delete them.

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If you use this method you must swap the selection before deleting points if you want to keep the ones inside the polygon (or be sure to use your regions "not of interest"). –  MappaGnosis Sep 12 '13 at 7:25
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