Re: [R-sig-Geo] anisotropy modeling

[shweta jp]

Is the same true for autofitVariogram {automap} ?

Shweta

On Wed, Jul 13, 2011 at 1:13 PM, Edzer Pebesma <
edzer.pebe...@uni-muenster.de> wrote:

> help(fit.variogram) has the following description:
>
>     Fit ranges and/or sills from a simple or nested variogram model to
>     a sample variogram
>
> I suspected it would completely ignore anisotropy settings. However,
> this seems not to be the case:
>
> > library(gstat)
> Loading required package: sp
> Loading required package: spacetime
> Loading required package: zoo
> Loading required package: xts
> > loadMeuse()
> > v0 = variogram(zinc~1,meuse, alpha = 0, tol.hor = 45)
> > v90 = variogram(zinc~1,meuse, alpha = 90, tol.hor = 45)
> > v = variogram(zinc~1,meuse)
> > fit.variogram(v, vgm(1, "Exp", 300, anis=c(90,1)))
>  model  psill    range
> 1   Exp 166238 323.6674
> > fit.variogram(v, vgm(1, "Exp", 300, anis=c(90,.1)))
>  model  psill    range ang1 anis1
> 1   Exp 166238 3236.674   90   0.1
> > fit.variogram(v0, vgm(1, "Exp", 300, anis=c(90,.1)))
>  model    psill    range ang1 anis1
> 1   Exp 146068.7 2772.751   90   0.1
> > fit.variogram(v90, vgm(1, "Exp", 300, anis=c(90,.1)))
>  model    psill    range ang1 anis1
> 1   Exp 200767.2 4027.282   90   0.1
> >
>
>
> On 07/13/2011 11:34 AM, Matevž Pavlič wrote:
> > Hi,
> >
> > thanks for the reply. Can you explain this a little bit more :
> > " it assumes the variogram to fit to is in the major (correlation)
> direction (or averaged over all directions)."
> >
> > I don't know exactly ehat it means....
> > m
> >
> > -----Original Message-----
> > From: r-sig-geo-boun...@r-project.org [mailto:
> r-sig-geo-boun...@r-project.org] On Behalf Of Edzer Pebesma
> > Sent: Wednesday, July 13, 2011 10:10 AM
> > To: r-sig-geo@r-project.org
> > Subject: Re: [R-sig-Geo] anisotropy modeling
> >
> >
> >
> > On 07/12/2011 10:52 PM, Matevž Pavlič wrote:
> >> Hi all,
> >>
> >>
> >>
> >> i 'm am not entirely sure I understand anisotropy kriging in R.
> >>
> >> I have a data set in which is (at least i think so) anisotropy is
> clearly visible. So I made directional variograms....
> >>
> >> So as i understand, the only thing that is different from >normal<
> kriging is the  >anis< property in which you define the diffrenece of
> ranges? Is that coreect?
> >
> > Yes. Please note that fit.variogram ignores anything about anisotropy, it
> assumes the variogram to fit to is in the major (correlation) direction (or
> averaged over all directions).
> >
> >>
> >> Bellow is the code i use :
> >>
> >>
> >>
> >> a<-5000/7000
> >>
> >> print(plot(variogram(Z ~ 1, DF, map = TRUE, cutoff = 15000, width =
> >> 100), main = "Variogram map, podlaga",col.regions =
> >> terrain.colors(64)))
> >>
> >> v1.a<-variogram(Z~1, DF, alpha=c(45, 135))
> >>
> >> (vmf.a <- fit.variogram(v1.a, vgm(2900, "Pen", 5500, 300, anis =
> >> c(135, a))))
> >>
> >> print(plot(v1.a, pl = F, pch = 20, col = "blue"))
> >>
> >> print(plot(v1.a, plot.numbers = F, pch = 20, col = "darkblue", model =
> >> vmf.a))
> >>
> >>
> >>
> >> podlaga.aniso<-krige(Z~1, DF[-zerodist(DF)[,1],], grd, vmf.a )
> >>
> >> print(spplot(podlaga.aniso, zcol="var1.pred",
> >> col.regions=terrain.colors(64), contour=T, pretty=T, cuts=15,
> >> key.space="right"))
> >>
> >> print(spplot(podlaga.aniso,  zcol="var1.var",
> >> col.regions=terrain.colors(64), contour=T, pretty=T, cuts=15,
> >> key.space="right"))
> >>
> >> writeGDAL(podlaga.aniso, "podlaga_aniso.tif")
> >>
> >>
> >>
> >> thanks for info,
> >>
> >>
> >>
> >> m
> >>
> >>
> >>      [[alternative HTML version deleted]]
> >>
> >> _______________________________________________
> >> R-sig-Geo mailing list
> >> R-sig-Geo@r-project.org
> >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >
> > --
> > Edzer Pebesma
> > Institute for Geoinformatics (ifgi), University of Münster Weseler Straße
> 253, 48151 Münster, Germany. Phone: +49 251 8333081, Fax: +49 251 8339763
> http://ifgi.uni-muenster.de
> > http://www.52north.org/geostatistics      e.pebe...@wwu.de
> >
> > _______________________________________________
> > R-sig-Geo mailing list
> > R-sig-Geo@r-project.org
> > https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>
> --
> Edzer Pebesma
> Institute for Geoinformatics (ifgi), University of Münster
> Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
> 8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
> http://www.52north.org/geostatistics      e.pebe...@wwu.de
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo@r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

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