Strategy for removing points inside PointCloud

For any pointcloud, I’d like to keep only a band of the “outermost” existing points around the cloud, like the blue marked ones:

I would have no other input data than the cloud itself, and a desired width of that “blue band” of points to keep, [Edit:] so I wouldn’t have any curve boundary etc to know where to cull. It must all be derived from the cloud itself.

At first glance I didn’t really grasp how the definition works which you posted, but I’ll have a closer look asap. Thank you for posting!

// Rolf