If you mix and match techniques in the right way I think you could get several grey scale maps out of one image.
Any masks generated are meant to be used as inputs to other Shader networks to control effects.

These techniques work best on figures that have a single continuous material (i.e. no material zones)
Using color separation would allow two masks to fade into one another, given a careful choice of colours.

Anyone who is familiar with Terragen will understand how multiple layers of masks can be used to produce amazing effects.