2

I would like to create random points with a minimum distance based on an attribute field (polygons with a larger area need random points with more space between them).

In theory this can be done. The random points tool has such a feature. But it doesn't recognize a text attribute. The buffer tool has a similar feature, and recognizes if you put the number + "Miles" in a text attribute column.

Random Point minimum distance only recognizes number attribute columns, and it is not clear which units it is converting those distances to. I imagine they should be in meters, for my data and data frame are both in British National Grid, yet points are created in polygons closer than what is stated in the field.

Perhaps I'm missing something.

1

My results are different from yours.

  • I used two fields called Points (Number of Points Field) and Distance (Minimum Allowed Distance Field) depending on container polygon size to create random points.
  • I computed two other fields called FREQ and mDist. First stores number of points produced per polygon, second shows minimum distance to other points within same polygon.

Out of 105 polygons

enter image description here

13 show less points than requested (no warning given) and no single violation of distance rule:

enter image description here

It seems that minimum distance requirement has higher priority over point count.

This is understandable, because there are no room left after certain amount of points have been computed.

There is a limit to points one can placed at certain distance

  • Sorry for commenting late on this Felix. I didn't because your post, though extensive, didn't really answer my question (it went beyond it) – woot May 27 '16 at 8:45
1

To answer my own questions (as far as I can tell)

No: The random point generator does have the same feature as the buffer tool. It cannot accept text

Yes: the units random point minimum distance uses are the map units. I was wrong about this (idiot -- can I downvote myself? I can't). One needs to be aware of the map units and convert appropriately

0

I just ran "Random Points", using numeric fields for Max Points and Minimum Distance. My Data, values and DataFrame are all in Meters. I have Points, inside the same Polygon, that are closer than the Minimum Distance. I'm seeing the same results as @woot, very strange.

  • You can use numeric field to define minimum distance – FelixIP Apr 13 '16 at 23:04

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.