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Re:AI-GEOSTATS: TIN-ACCURANCY2

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  • bob sandefur
    Hi- No one responded as of 1500 on 28 Jan so a few ideas: I assume you have irregular data and are using a TIN to generate a grid. Since a point in a TIN
    Message 1 of 2 , Jan 28, 2004
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      Hi-

      No one responded as of 1500 on 28 Jan so a few ideas:

      I assume you have irregular data and are using a TIN to generate a grid.
      Since a point in a TIN triangle is a linear combination of the 3 points the
      linear estimation variance using the variogram of the TIN X Y Z points and
      weights should work as error estimator.
      Possible pit falls
      1.) If you are modeling topography it is often non covariance stationary.
      2.) If the xyz data are contour lines you should honor the contours when you
      TIN.
      3.) Three points are probably less than optimal for min estimation variance.

      A cross validation where you drop out a point, TIN with nearby data and read
      the z at the x y of the thrown out point and compare to actual z at that
      point should also work if the data isn't on contour lines. (and cross
      validation isn't too hard or time consuming in arcGis).

      Hope this helps

      Robert (Bob) L. Sandefur PE
      Senior Geostatistician / Reserve Analyst
      CAM
      200 Union Suite G-13
      Lakewood, Co
      80228

      rsandefur@...

      303 472-3240 (cell) <-best choice

      303 716-1617 ext 14



      -----Original Message-----
      From: ai-geostats-list@... [mailto:ai-geostats-list@...]On Behalf Of
      Ines
      Sent: Tuesday, January 27, 2004 3:20 AM
      To: ai-geostats@...
      Subject: AI-GEOSTATS: request - accurancy TIN


      dear list

      I must generate a DEM using the TIN interpolator, using geostatistical
      analyst extension of ArcGis software can I define the DEM accurancy (raster
      output not only thr RMS error) like I do with the kriging interpolator?
      if it is not possible tell me a method to do this,which software can I use?

      thank you for your availability



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