I have a .csv file with observations of various species and I want a polygon to illustrate the area where those species occur. I ran the Convex Hull, grouped by the species' names field, which returned a feature for each species, as expected.

The problem is that there were some species that weren't expected to return an error because they don't have enough geometries to form a polygon, but the number of errors was higher than the number of species with 1 or 2 observations.

What causes the Convex Hull in QGIS 3.14 to return an error?

  • 3
    Reproducible example? – Paul H Sep 23 at 16:15
  • 1
    Some suggestions: a) many observations at a single point b) three or more observations on a straight line. – user30184 Sep 23 at 17:10
  • I uploaded two tables i used that have given this error in We Transfer. Link next: we.tl/t-0WLxW9SVDP – Eric Lino Sep 23 at 17:41
  • I checked the database manually and along with the cases you mentioned, I also noticed that Convex Hull won't create a feature if there are points with identical coordinates. I suggest including it on your final answer – Eric Lino Sep 23 at 20:14

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