[Qgis-user] qgis random points in layer bounds not all points created

[Andrea Giudiceandrea]

Newcomb, Doug wrote
> I have 81 points that I buffer by 25m. I then run the random points in
> layer bounds tool to generate 100 points. I get 43 and a message that not
> all points were created.
> I ask for 300 points, and I get 160 .

The algorithm tries to randomly place each point for up to 200 attempts. So,
more points to be created, more attempts.

Obviously, did you specify the same minimum distance value in both your test
for 100 and 300 points?

The chance to place the whole number of requested points depends on the
geometric characteristics of the polygons ad how are distributed in the
space and the constraint of the minimum distance between each point. If this
value is too large (e.g. in your case, > 50 m) then the problem may have no
solution.

By the way, it seems to me that the description of the algorithm in the user
manual is not accurate and should be improved.
It states that the tool creates random points within the _extent_ of a given
layer, but it is not so.

Regards.

Andrea



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