3

I have several fields of points that look like so:

enter image description here

They are actually thousands of points that appear as polygons because they're so close to one another. They're research points 720 feet from one another in all directions.

So clearly on this map we can see 7 would-be polygons. How can I get qgis to create these polygons without me having to draw them by hand?

  • 1
    Why not just make convexhull ? Vector > Geoprocessing Tools – WKT May 3 '16 at 18:56
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    The options for convex hulls allow me to create a single convex hull, which isn't what I want, or to create multiple convex hulls based off input fields, which I don't have in the attributes. Any way to use buffer rules to create these? – boulder_ruby May 3 '16 at 18:57
  • You have an option "based on input field".... (and for that density, concave isn't very important) – WKT May 3 '16 at 19:04
  • I'm looking for a way to do the same operation but with a large dataset where the resulting polygons would overlay. Since there are about 300 polygons to generate, I wonder if anyone managed to do this operation over such dataset, creating multiple poligons. Cheers – Julian Nicholas Jul 5 '18 at 15:16
5

You can use the Concave hull (Concave, not Convex) tool in the QGIS geoprocessing algorithms.

When setting the threshold, make sure it's big enough to encircle all the close points, but not too big to encircle separate clusters.

Example: Here are the points:

enter image description here

And after the Concave hull tool, 3 separate polygon features. enter image description here

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