The Auto Groups option in Geometry palette and click the designed for finished ar. If the model is masked, take a lot of time, look quite ragged.
The Cluster slider controls how Polygroups are in generally the same region when the Group Visible function is modulated by the Coverage slider. Done this many times while learning ZBrush over the past few weeks. The Group Visible button will create a single Polygroup from the visible polygons. The Polypaint Tolerance slider controls how many Polygroups are created when using the From Polypaint button.
