interpolation, rast.to.sites

[Nalneesh Gaur]

You can convert a ratser map to sites map very easily by the following
command line:

	r.stats -1gz input=map |s.in.ascii sites=<sites_file>

Thus a sites list file is created. 
Writing more about s.surf.tps would best be helena mitasova's job
who has actually created this program. Its different from the idw's in the sense that it passes a sheet thru all the data points in the area. The user
can figure out what should the tension of the sheet be and what the material
should be (of the sheet).

Nalneesh Gaur, University of oklahoma, Norman