These functions open a geometry file and return a list of points with the location P within radius, based on point positions found in Pchannel. Only the maxpoints closest points within the given radius will be returned. The file name may use the
op: syntax to reference SOP geometry in the OP contexts. The Pchannel parameter indicates the attribute which contains the positions to be searched.
ptgroup is a point group that limits the points to search. This is a SOP-style group pattern, so can be something like
@Cd.x>0.5. A blank string is treated as matching all points.