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[ai-geostats] 3D cross-variograms fittind

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  • seba
    Dear list members Despite free opensource software (for example Gstat) could perform full indicator Kriging (i.e. using cross variogram) I have not found free
    Message 1 of 2 , Mar 1, 2006
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      Dear list members

      Despite free opensource software (for example Gstat) could perform full
      indicator Kriging (i.e. using cross variogram) I have not
      found free software for fitting 3D cross variograms. Surely, commercial
      software can do that, but it could
      be a little bit expensive from the economic point of view !
      Do you know any opensource software that performs fitting of a 3D
      coregionalization model?
      Or, have you an idea where to start in order to write a code to do that?
      Let me know if you know some opensource software (better in C++, but also
      in fortran 90 or c) that could be a starting point.
      Thank you in advance for your help
      S. Trevisani
    • seba
      Hi Luke Yes, as you suggest very often in geology the third dimension (say z) is more similar to a temporal dimension than to a spatial one. (Think for example
      Message 2 of 2 , Mar 1, 2006
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        Hi Luke
        Yes, as you suggest very often in geology the third dimension (say z) is
        more similar to a temporal dimension than to a spatial one.
        (Think for example to quaternary sedimentary deposits). So is it so a big
        deal to preform a 3d analisys? isn't it better to conduct
        a stratified 2D analysis?
        For this reason I`m glad if someone has some idea also only for 2D
        cross-variogram fitting.
        Bye
        Sebastiano



        At 12.19 01/03/2006, Luke Spadavecchia wrote:
        >Hi seba,
        >
        >I have found similar problems. What kind of 3D model are you trying to
        >fit? If it is a separable covariance model (of the product or product-sum)
        >variety, a good place to start is the modified GSLIB code that appeared in
        >the attached article. The code can be downloaded from the computers and
        >geosciences website. The code will compute the empirical semivariance
        >surface for you, but there is no fitting routine. I am about to embark on
        >a major programming task (when I get the time) to fit a variogram surface
        >to the output of GAMSURF, but in the meantime, I just fit my model in
        >Excel, or some other spreadsheet. I have attached an example for you:
        >although it is spatio-temporal, the same model is permissable in 3D space.
        >Any nested variograms permitted in 2D can be used for the separable
        >models. This is actually quite appealing, given the nature of the
        >covariance in the vertical may be different in functional form from the
        >horizontal covariance, since different processes may underlie the
        >autocorrelation.
        >
        >Hope that is helpful
        >
        >Luke
        >
        >
        >
        >
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