Shapes in space

I have a small Visad program that will plot particles in space like
this:

(index) --> ( x, y, z, value )

I run my data files through a cluster algrothm and have textual
information concerning the clusters, but I would like to emphasize these
clusters in the visualization. I think I would like to draw boundaries
around these cluster and was wondering if there is a method in VisAD
that will allow me to accomplish this?

Thanks,
-dave

P.S. any other suggestions on how I could visualize my clustering
results would be appreciated.

--------------------
David Nguyen
Computer Engineering
Northwestern University
dave@xxxxxxxxxxxxxx