I need to calculate Variety of pixels for every polygon in a shapefile but the analysis returns zero.

Polygons are much bigger than a raster cell which is 10 m. Polygons are completely covered with raster cells. Raster cells have 8 categories - from 1 to 8 (reclassified aspect). No Data from original aspect raster were converted to 0 (at least this was set in a reclassification dialog). Polygons, raster and project have the same coordinate system (EPSG 5514) and are stored on a disk, no temp layers. Polygons have valid geometry with no errors. Raster is a geoTIFF.

raster and polygons

I have searched all the questions with "Zonal stats returns zero or empty values", tried the solutions in there but with no luck. I have no idea what´s wrong.

The analysis doesn´t work for me in QGIS 3.10.4 LTR, the log says nothing wrong, it just doesn´t do what it should. When I tried the same in QGIS 2.18 the analysis fails with a KeyError:


Any tips?

  • Saving raster to different format (I tried ESRI hdr and geopackage) doesn´t solve it. – jonlew Apr 29 at 11:03
  • Saving polygon shapefile to different format (I tried geopackage) doesn´t solve it. – jonlew Apr 29 at 12:07
  • Converting polygons to wgs84, raster to wgs84 or both to wgs84 didn´t help. – jonlew Apr 29 at 12:29
  • I´d be happy if you tested it yourself in your QGIS versions... Zip with data is here: transfernow.net/RlrNmx042020 – jonlew Apr 29 at 12:55
  • Have you made sure the polygons are valid? Try Fix geometry – BERA Apr 29 at 13:39

Fixing geometry in QGIS showed no issues as well as checking validity or all those fixing things in QGIS. I had to Repair geometry in ArcGIS - polygons had several self-intersections that QGIS hadn´t recognized. Zonal statistics with repaired polygons works well now.

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