Three dimensional Polyfillv

Good day.

I have been following this newsgroup for a while and it is really very
helpful in solving many problems that I have encountered in IDL
programming.

Currently I am writting an IDL procedure to sample some points on the
surface of a 3D blob (from a 3D volume).This is later used to contruct
3D point distribution model (PDM) of the blob. The PDM is actually a
(3, n) array of rectangular coordinates. I would like to reconstruct
the blob by using the PDM. To do this, I need the subscripts of the
array elements contained inside the PDM. This can be done by using
Polyfillv for in the case of 2D array. Is there any similar function
for 3D volume?

Your kind assistance in this matter is highly appreciated.

Thank you in advance.