Tuesday, 15 October 2019

QGIS point sampling tool really slow for polygons?


I have a large field of randomly distributed points (100,000 of them to be precise), and I'd like to get values for a variety of raster and polygon coverages for each point. I've been using the QGIS Point Sampling Tool, and it seems to work very nicely for rasters (runs in under a minute) but to take literally hours for many of my polygon coverages.


Can someone explain to me why this is taking so long?


Is there a more efficient open source tool to do this?



Answer



I wonder if you might be able to use the Add polygon attributes to points tool in the Processing toolbox? (much faster than the standard spatial join according to this blogpost: http://anitagraser.com/2013/10/02/add-polygon-attributes-to-points-vs-join-attributes-by-location/)


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