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[ai-geostats] Re: kriging with trend

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  • Isobel Clark
    Oriol If you can get a semi-variogram from the observations which does not contain a parabolic upturn (diagnostic of polynomial type trend) then your trend is
    Message 1 of 3 , Jan 5, 2006
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      Oriol
       
      If you can get a semi-variogram from the observations which does not contain a parabolic upturn (diagnostic of polynomial type trend) then your trend is weak enough to ignore.
       
      You can download a free tutorial on dealing with polynomial type trend at http://geoecosse.bzland.com/softwares
       
      Isobel

      Oriol Falivene <oriolfalivene@...> wrote:
      Dear list,

      Just a simple question...

      I'm trying to produce a contour map from a structural surface. This
      surface is highly non-stationary (actuaally dips towards NW)
      I wolud like to know which could be the best solution for getting a
      reliabel map:

      1) Fit a plyonomial surface to the sample values, which is used as a
      drift. Substract the drift from the observations to get the residuals.
      Estimate the variogram of the residuals (now the residual variable is
      stationary). Perform OK on the residuals. Add the polynomial surface to
      the residuals to get the interpolated surface.

      2) Compute variograms from the observations. Use universal kriging to
      get the interpolated surface.

      Thank you

      Oriol
      --



      ______________________________________

      Oriol Falivene
      ofaliven@...
      http://www.ub.es/ggac

      tel. (+34) 93 4021373
      fax (+34) 93 4021340

      Fac. de Geologia,
      Univ. de Barcelona



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