Importing Elevation data from an ASCII format

[Brian Culpepper]

Tom Nelson writes:> 
> 
> with a sites file then do either s.surf.idw or s.surf.tps.
> Both create a surface file but tps takes a lot longer and with possibly better results.
> then r.contour which produces a vector contour map of interpolated contours from the 
> surface file.
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I will have to disagree with "do either s.surf.idw or s.surf.tps". These two
interpolation modules are NOT the same! If you are creating an elevation surface
then I believe s.surf.tps is the one to use, because all "sites" are equally 
weighted, whereas ".idw" refers to inverse distance weighting. The ".idw" could
create unsatisfactory results. I suggest testing these two modules on a sample
dataset and comparing results.

A good reference is Helena Mitasova article in the Spring 1993 GRASSCLIPPINGS.

Hope this helps...

-- 
R. Brian Culpepper                                 Research Assistant
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Center for Advanced Spatial Technologies           (fax) 501 575-3846
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University of Arkansas                            brian at cast.uark.edu
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All opinions are my own and do not necessarily reflect those of the
Center for Advanced Spatial Technologies or the University of Arkansas.