David Minkler wrote:
> What's fast?  Do you have equations which describe the surface?  Do you
> need a one time solution or is this going to be done repeatedly?
Dave, good question: I should have explained that a bit, actually.  I
*think* that the true value computation can be O(n) (i.e. linear) where 'n'
is the number of loci describing the hull.  I'm not completely sure about
that, but that's what I'm assuming is the case.  Of course I'd like the
approximation to require 0 time :^), but realistically if I found one that
was 20% the cost of the true value comp, I'd be very happy.
  I don't have equations, just data points in 3D space; I can vary the
"resolution" of the hull description quite easily - i.e., just generate
fewer data points, which will obviously save time for any algorithm, but
introduce error at the same time.
  This isn't a 1-time thing, it's part of a larger algorithm that will need
to invoke the approximation at a pretty high frequency (no, not in real
time, thank goodness!)
Jim

> OP:
> Jim Tellier wrote:
> > Any math wizards here?  I've been searching for quite a while now, but
coming up empty ... I'm looking for an APPROXIMATION algorithm to compute
the surface area of a convex hull shape.  Given a 3D matrix (may be either
sparse or complete, but would be best if I could use sparse to save space)
of surface loci, I need a "reasonably accurate" (say +/- 15-20% variance
from actual true value) but *fast* approximation.   Parallel or distributed
algorithms would be ideal, but not a requirement.   3D geometry was never
really in my bag o' tricks :^)
> > Thanks for any suggestions or pointers!
> > Jim
>
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