I have multiple (clouds of) points, and would like to take the outer envelope of these points. This will allow me to polygonize my points.
Using the convex-hull would help me, but in some cases, my shapes are not convex, and hence this convex-hull envelope contains large areas without any points. The question mark is a good example where one would not necessarily want a convex hull (from: link):
My questions are:
- Is there a concept of non-convex hull? How is this called, and conceptualized? I guess that while it is easy to define a convex hull (it is unique), it is difficult to conceptualize a non-convex hull, as this won't necessarily be unique, so any definition will be harder/involve some free parameters.
- What are the algorithms to implement this, ideally in R?