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AI-GEOSTATS: neighbourhood

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  • Ines
    dear list when I define for example a lag size = 10 m and the lag number = 10, the maximum distance which I read on the x axis of semi-variogram value is
    Message 1 of 3 , Apr 7 4:50 AM
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      dear list



      when I define for example a lag size = 10 m and the lag number = 10, the maximum distance which I read on the x axis of semi-variogram value is 100m, the last value what point out?



      which weight has the neighbourhood in the kriging interpolation after that I have defined all the parameters necessary to estimate the variogram ? And can I define it?

      Radius and numbers of neighbour?





      Best regards

      ines





      [Non-text portions of this message have been removed]
    • Gregoire Dubois
      Ines, don t expect many replies on this one. I m strongly inviting you (again) to read the manual of the software and to learn the essential vocabulary used in
      Message 2 of 3 , Apr 7 6:54 AM
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        Ines,

        don't expect many replies on this one. I'm strongly inviting you (again)
        to read the manual of the software and to learn the essential vocabulary
        used in geostatistics.
        It is a bit of a jargon but you will need it to understand the replies.

        You can learn the essential vocabulary and concept by using variowin
        and/or Geoeas (check the software section of www.ai-geostats.org )

        A manual of variowin is available from
        http://sal.agecon.uiuc.edu/csiss/pdf/variowin.pdf

        Check also geoeas for the part on kriging (variowin doesn't go that
        far).

        Nevertheless, here is a quick reply to your questions:

        Lag size = mean separation distance between pairs of points (plus/minus
        a tolerance on the distance since you most probably will not have
        samples separated by exactly 10 meters). If you don't know what I mean
        with pairs of points, then please check variowin's manual (or the FAQ I
        have mentioned earlier) .

        Lag number = the number of points you want on your experimental
        semivariogran. If you select 10, you will have 10 points. The last point
        of your experimental semivariogram is then

        10 (number of lags) x 10 (lag distance) meters = 100 meters. Hence the
        100 meters on your plot.

        The last lag will contain all the pairs separated by 100 meters. The 9th
        point will correspond to pairs seperated by 90 meters, etc.

        Neighbours: you can search neighbours in different ways: by defining a
        number of nearest points, by defining a circle (define a length of a
        radius) or even an elipse (you have to define the shortest and longest
        radius of the ellipse)...

        Interpolating data is not something you can do without thinking twice
        and without experience. If you don't want to learn all these concepts
        (or don''t have the time to) but still have to do the maps, I would
        recommend you to use something less complex like the inverse weithed
        distance interpolator. In any case make sure you understand what you did
        to be able to understand the output (the map).
        In any case don't use a black box approach, even if the results may
        "look nicer". This is a very personal opinion of course but I believe it
        is shared by most practitioners.

        Gregoire



        -----Original Message-----
        From: ai-geostats-list@... [mailto:ai-geostats-list@...] On
        Behalf Of Ines
        Sent: 07 April 2004 13:50
        To: ai-geostats@...
        Subject: AI-GEOSTATS: neighbourhood


        dear list



        when I define for example a lag size = 10 m and the lag number = 10, the
        maximum distance which I read on the x axis of semi-variogram value is
        100m, the last value what point out?



        which weight has the neighbourhood in the kriging interpolation after
        that I have defined all the parameters necessary to estimate the
        variogram ? And can I define it?

        Radius and numbers of neighbour?





        Best regards

        ines





        [Non-text portions of this message have been removed]
      • Koen Hufkens
        http://honeybee.helsinki.fi/GIS/y196/Using_ArcGIS_Geostat_Anal_Tutor.pdf I hope it helps, Koen. ... -- * To post a message to the list, send it to
        Message 3 of 3 , Apr 7 9:57 AM
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          http://honeybee.helsinki.fi/GIS/y196/Using_ArcGIS_Geostat_Anal_Tutor.pdf

          I hope it helps,
          Koen.

          On Wed, 7 Apr 2004 13:50:21 +0200, Ines <ialberic@...> wrote:

          > dear list
          >
          >
          >
          > when I define for example a lag size = 10 m and the lag number = 10, the maximum distance which I read on the x axis of semi-variogram value is 100m, the last value what point out?
          >
          >
          >
          > which weight has the neighbourhood in the kriging interpolation after that I have defined all the parameters necessary to estimate the variogram ? And can I define it?
          >
          > Radius and numbers of neighbour?
          >
          >
          >
          >
          >
          > Best regards
          >
          > ines
          >
          >
          >



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