Find the group of closest points within a search radius.

Input parameters:

1. Pt → Starting point for nearest point search.
2. Cl → Point cloud to search.
3. Gr → Maximum size of local group.
4. R- → Optional minimum radius. Points closer than this value will be omitted from the local group.
5. R+ → Optional maximum radius. Points further than this value will be omitted from the local group.

Output parameters:

1. Pt → All the points in the local group.
2. Ix → Indices of points in the local group.
3. Dx → Distance from the search point to each point in the local group.