Does anyone familiar with the QGIS Zonal Statistics tool know why stats calculations might return empty?


  1. DEM for South Carolina: http://dnr.sc.gov/GIS/descdem.html
  2. A vector shapefile: https://s3.amazonaws.com/www.improvz.com/gis/Archive.zip

Desired result: Zonal Statistics calculates elevation on all shapes.

Actual result: Zonal Statistics plugin returns empty values for all fields

Parcels and DEM loaded Zonal Stats plugin prompt Zonal Stats calculating No elevation stats are calculated

QGIS 2.8 on MacOSX.

  • Try upgrading to QGIS 3.2 and re-test. There's been lots of fixes since 2.8 – ndawson Jul 30 '18 at 23:34
  • tks, @ndawson Upgrade plus the suggestions below fixed the issue. – Adestin Jul 31 '18 at 17:41

Your file "CAD_PARCEL_MP have some topology error (check with menu Vector >"topology checker).

I fix it with the processing tool "fix geometry" in QGIS 3.2, and than it seems working

enter image description here enter image description here


It is interesting to know that fix geometries solved this issue, thanks to Volta.

My suggestion is (was) to reproject the polygon layer to match with the DEM layer; since most FAQ about Zonal Statistics are related to different CRSs between raster and polygon layers.

A quick test, reprojecting the CAD_PARCEL_MP to EPSG: 2029 *NAD27(76) UTM zone 17N* looks OK.

enter image description here

... an alternative option, just in case :)


Seeing the comment by ndawson, my last line just in case should be just in case the work has to be done in pre-QGIS 3. The CRS issue is gone now.

  • tks, @Kazuhito...helpful! – Adestin Jul 31 '18 at 17:43
  • This is no longer required in QGIS 3.2 - if you have different CRS between the raster and vector, it will automatically be handled correctly. – ndawson Jul 31 '18 at 21:32

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