Hi Tim,
I have been in a similar situation, and modified some functions in geoR
in order to fit variograms, and perform kriging with non-Euclidean
distances. In particular, you can use likfit() and get
maximum-likelihood estimates for variogram models with non-Euclidean
distances.
You can get the modified package (source) from
http://www.geeitema.org/doc/guenmap//docs/modif.geoR.1.6-27.tar.gz.
Please note that this modifications do not perform positive-definiteness
checking.
You should do that manually.
That is something I should implement.
Please let me know if you try it, and if you need any help.
ƒacu.-
On 15/07/10 01:24, Timothy W. Hilton wrote:
Hello R-sig-Geo list,
I want to calculate maximum likelihood estimations for variogram
parameters (sill, range). My data locations span North America, thus I
believe that UTM coordinates (or any other projection) will distort
distances between sites too much for me to use Euclidian coordinates.
As far as I can tell, geoR will not accept non-Euclidian coordinates or
allow the user to specify a distance function. gstat accepts latitude
and longitude to define locations, but does not include maximum
likelihood estimation for the range (fit.variogram.reml estimates sill
only).
Is anyone aware of an R geostats package that handles my situation?
Many thanks!
Tim
--
Timothy W. Hilton
PhD Candidate, Department of Meteorology
The Pennsylvania State University
503 Walker Building, University Park, PA 16802
hil...@meteo.psu.edu
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