angluar redundancy: point-to-line distance dilemma

Problem

1. If the idea of "common radius" is defined by mutual distance among multi-multi evaluation, the overlapping nature of the rectangular pixel tesselation will make the common radius group grow excessively thick.
2. meaning point-by-point + line equation based grouping is likely to cluster the whole set of points
   

Solution

1. grouping should not work on the multi-multi assumption.
   
2. at each azimuth, there should be a reference point, against which all the other points' p2l-distances are calculated.
   
3. an angular group is defined by the innermost/outermost point on that common radius
4. dilemma: hard-coded angular quantization tends to mis-cluster; soft-quantization by multi-multi free clustering clusters everything