Thanks for the reply, I guess I was a little vague with what I need.

I have a subset of 300 points, there are 26 subsets altogether (so about 7,000 points altogether). These points make up block formations inside a city, but I don't need to go down to the detail of a block, I just need the outside shape of the whole subset.

So first I need to get a convex hull, which give me a rubberbanding effect type polygon, which is a great place to start.

Once I have the convex hull, I will take the first point in the hull and then find the closest point to it in the original list of points.

If that point is not the next point or previous point and is not further away on the edge than the next point or previous point and is not on the edges to the current point in the list, then we would add it to the tail of the list in the concave hull, and then order the list of points after it goes through the previous logic for all of the points that came out of the convex hull algorithm.

I have it all in my head I think, just implementing it has been much more of a bear than one would expect.