Z aware interpolation - clarification

Monica,

gstat has interpolation facilities for real 3D data: IDW, as
well as variogram modelling & kriging prediction and simulation.

Try:

library(gstat)
demo(gstat3D)

gstat exists as an R package, as well as a stand alone binary.
The package is at CRAN, the rest at www.gstat.org

best regards,
--
Edzer