title: Algorithm to add points at the edge of other points
body: <p>Let's say the initial map has only the red dots. Then I want to add all the green dots. Note that the shape is not always circular.</p>
  
  <p>Any idea how to do that?</p>
  
  <p>I was thinking to consider all as a cluster and then get the edge (or approximation) of the cluster and add new dots.</p>
  
  <p><a href="https://i.stack.imgur.com/ytMzU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ytMzU.png" alt="t th"></a></p>