Eduardo, thanks a lot. Before I decide what will I use - what about applying
fault lines? Is it possible to incorporate those as lines where stops
interpolations?
Actually, I don’t now how exactly GRASS deals with missing values (mv) in their
attribute tables, but you should be able to achieve that whit the R packages. On
the other hand, you can specify a value to be equal to mv in Gstat (for example
-9999); the default is the NA string. In Gstat, the interpolation locations are
controlled via a mask map.
You can read the Gstat user’s manual for details. An introduction to the use of
R with GRASS for spatial data analysis in
http://grass.itc.it/statsgrass/grass_geostats.html.
There is also a statgrass mailing list:
http://grass.itc.it/mailman/listinfo/statsgrass.
Eduardo