No Subject

I'm trying to guess what you mean about Inventor's limitations re point data;
is it that it's hard to get a clear visual impression from large clouds of
points, and the points aren't organized such that you can readily reduce
them to a surface?

If so, you might look at NCSA's "alpha shape" package; it basically
takes a cloud of points and a parameter indicating something like
the scale of concavities, and yields a sort of generalized convex hull.
They offer this -- a paper describing the idea, and SGI binaries for
producing alpha shapes and viewing them interactively -- by anonymous FTP
from ftp.ncsa.uiuc.edu under /SGI/Alpha-shape/*.  [You don't need to use
their viewer; they can produce results in the form of a collection of
tetrahedra, triangles, etc., so you can manipulate it yourself.]
I've never used this, and don't know how well it works nor whether it
can actually handle data sets as large as yours, but it seems worth a try.  

   Stuart Levy, Geometry Center, University of Minnesota