Loading ...
Sorry, an error occurred while loading the content.

GEOSTATS:cross variogram

Expand Messages
  • nowook park
    Dear all.. I have some question about cross variogram analysis.. in geoscience data integration scheme, for the purpose of the evaluation of quantitative
    Message 1 of 2 , May 4, 1999
    • 0 Attachment
      Dear all..

      I have some question about cross variogram analysis..

      in geoscience data integration scheme,
      for the purpose of the evaluation of quantitative spatial influences of
      each data layer to integrated layer.
      if I perform cross variogram analysis with respect to
      classified data, not continous data,
      (ex) class 1 : 0 ~ 10 , class 2 : 10 ~ 11 etc..
      control variable : integrated layer , target variable : each input
      layer)
      is it reasonable ? or is it useless ?
      I wonder whether application to the classified data of cross variogram
      is valid, or not..
      also,if the grid cell size is 30m * 30m,
      what is the reasonable unit lag interval w.r.t. sampling space?

      If anyone has cross variogram fortran codes,
      please let me know..

      Thank you..

      best regards,

      nowook..


      --
      *To post a message to the list, send it to ai-geostats@....
      *As a general service to list users, please remember to post a summary
      of any useful responses to your questions.
      *To unsubscribe, send email to majordomo@... with no subject and
      "unsubscribe ai-geostats" in the message body.
      DO NOT SEND Subscribe/Unsubscribe requests to the list!
    • Pierre Goovaerts
      I am not sure that I have fully understood your question but I would recommend performing an indicator transform of your data before starting the (cross)
      Message 2 of 2 , May 5, 1999
      • 0 Attachment
        I am not sure that I have fully understood your question
        but I would recommend performing an indicator transform of
        your data before starting the (cross) variogram analysis.
        For each class, you can define an indicator of occurrence
        of that class at any location u; e.g. for your classes
        1 (0-10) and 2 (10-20):
        I(u;c_1)=1 if 0 < z(u) <= 10, and I(u;c_1)=0 otherwise
        I(u;c_2)=1 if 10 < z(u) <= 20, and I(u;c_2)=0 otherwise

        Then, you compute a semivariogram of these indicators:
        g(h,c_1) = (1/2N(h)) sum_alpha=1^N(h) [i(u_alpha;c_1)-i(u_alpha+h;c_1)]^2
        or cross semivariogram
        g(h,c_1,c_2) = (1/2N(h)) sum_alpha=1^N(h)
        [i(u_alpha;c_1)-i(u_alpha+h;c_1)] x
        [i(u_alpha;c_2)-i(u_alpha+h;c_2)]

        The indicator variogram (=twice the value of the semivariogram 2g(h,c_1))
        measures how often two locations a vector h apart belong to c_1
        and another category. The smaller 2g(h,c_1), the better the spatial
        connectivity of the class c_1. The cross variogram (2g(h,c_1,c_2))
        measures the transition frequency between c_1 and c_2.

        Cross indicator semivariograms can be computed using the public-domain
        gslib programs that can be downloaded from
        http://www.ualberta.ca/~smpe/people/clayton/software.html
        Examples of class indicator variograms can be found in the paper:
        Goovaerts, P. 1996.
        Stochastic simulation of categorical variables using a classification
        algorithm and simulated annealing.
        Mathematical Geology, 28(7):909--921.

        There is also a research report (SCRF 94 paper) that you can download
        from my webpage.

        If you want to invest more time in the use of
        indicator variograms to detect different types
        of processes (e.g. mosaic, diffusion-type..), two
        references are:
        Rivoirard (1993). Relations between the indicators related to a
        regionalized variable. In: Soares, A. (Ed.), Geostatistics Tr\'oia '92,
        Kluwer Academic Publishers, Dordrecht, pp. 273--284.

        Webster R, Boag B (1992) Geostatistical analysis of cyst nematodes
        in soil. J. Soil Sci. 43: 583--595

        Regards,

        Pierre


        <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>

        ________ ________
        | \ / | Pierre Goovaerts
        |_ \ / _| Assistant professor
        __|________\/________|__ Dept of Civil & Environmental Engineering
        | | The University of Michigan
        | M I C H I G A N | EWRE Building, Room 117
        |________________________| Ann Arbor, Michigan, 48109-2125, U.S.A
        _| |_\ /_| |_
        | |\ /| | E-mail: goovaert@...
        |________| \/ |________| Phone: (734) 936-0141
        Fax: (734) 763-2275
        http://www-personal.engin.umich.edu/~goovaert/

        <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>


        On Wed, 5 May 1999, nowook park wrote:

        > Dear all..
        >
        > I have some question about cross variogram analysis..
        >
        > in geoscience data integration scheme,
        > for the purpose of the evaluation of quantitative spatial influences of
        > each data layer to integrated layer.
        > if I perform cross variogram analysis with respect to
        > classified data, not continous data,
        > (ex) class 1 : 0 ~ 10 , class 2 : 10 ~ 11 etc..
        > control variable : integrated layer , target variable : each input
        > layer)
        > is it reasonable ? or is it useless ?
        > I wonder whether application to the classified data of cross variogram
        > is valid, or not..
        > also,if the grid cell size is 30m * 30m,
        > what is the reasonable unit lag interval w.r.t. sampling space?
        >
        > If anyone has cross variogram fortran codes,
        > please let me know..
        >
        > Thank you..
        >
        > best regards,
        >
        > nowook..
        >
        >
        > --
        > *To post a message to the list, send it to ai-geostats@....
        > *As a general service to list users, please remember to post a summary
        > of any useful responses to your questions.
        > *To unsubscribe, send email to majordomo@... with no subject and
        > "unsubscribe ai-geostats" in the message body.
        > DO NOT SEND Subscribe/Unsubscribe requests to the list!
        >


        --
        *To post a message to the list, send it to ai-geostats@....
        *As a general service to list users, please remember to post a summary
        of any useful responses to your questions.
        *To unsubscribe, send email to majordomo@... with no subject and
        "unsubscribe ai-geostats" in the message body.
        DO NOT SEND Subscribe/Unsubscribe requests to the list!
      Your message has been successfully submitted and would be delivered to recipients shortly.