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I've been using the 'Vector geometry--> Voronoi ploygons'function in QGIS to create voronoi cells for 200,000 points with success. However, recently I am working with a bigger point set (500,000 points randomly generated into a polygon repreesenting 1000km2) and the function consistently freezes without error at 99%.

I have tried outputting both to a temporary file (memory) and to a package file, but both still freeze at 99%.

Each point has coordinates and several attributes, so I thought perhaps the file was just too large for QGIS. I have tried running again with only the coordinates, but it still hangs at 99%.

Can anyone advise?

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I dont have a big data set for reference on this but I have found QGIS 3.2 to be much more stable and less prone to crashing. Try to see if it can output a result on that.

Also, check if all the geometries are valid otherwise it can cause errors.

Another option to try would be to just give the points one unique attribute, say "ID" and move the rest of the data onto a spreadsheet. Once the polygon is created, use table joins to bring in the rest of the attributes.

Have you tried doing this in another software like Mapinfo? That way you know its not the input file that is causing errors.

  • I've recently sworn off Mapinfos and ArcGIS, in favour of QGIS only workflows. However, I just tried the operation with SAGA's Thiessen polygons and it worked. Although Thiessen polygons are meant to be equivalent to Voronoi cells, I don't believe using a different function is a true solution, although it got me where I needed to go – Shawn Sep 25 '18 at 22:00
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There is a second implementation of Voronoi in QGIS using GRASS which is maybe more stable. Search the toolbox for "voronoi", then choose "v.voronoi".

  • This is a good suggestion, and what I attempted as a fix as well. However, I received an error in the GRASS window, with no helpful info. – Shawn Sep 25 '18 at 22:03
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Eventually, I was able to get an equivalent product using SAGA --> Vector Point Tools --> Thiessen ploygons

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