Please clarify the concept of Alpha parameters.
A simplest non-degenerate example computing alpha shapes, possibly just with 3 or 4 points would help.
The following sources seems to have conflicting information. Are two conventions prevalent in literature?
Source 1:
https://alphashape.readthedocs.io/en/latest/readme.html#using-a-varying-alpha-parameter
When the alphashape function is called with an alpha parameter of 0, a convex hull will always be returned.
Source 2: https://doc.cgal.org/latest/Alpha_shapes_3/index.html#Alpha_shapes_3Definitions Hence, the alpha shape becomes the convex hull of S as α→∞.
Source 3: https://www.clear.rice.edu/comp651/papers/Edelsbrunner-AlphaShapesOnShapeSetPointsPlane.pdf As α approaches zero, the alpha-hull approximates the common convex hull.