Re: GEOSTATS: Kriging query
- Fran Taylor wrote:
> I was wondering if anyone has happened to have tried kriging of valleys.I'm
> trying to create a surface of a u-shaped valley using kriging.valley, the .
> An obvious observation (but none-the-less important) is that being a
> surface is not flat, either in long-profile or cross-section, which leadsme to
> ask, does this matter? should I account for drift, and do I do this usingSince the valley is U-shaped, I am sure the valley wouldn't take too kindly
> universal kriging?
to being treated as a flat surface, being a valley and all. Either krige
a limited search neighborhood or do a full universal kriging using, say,
a polynomial drift of order 2 to describe the valley's trend. Use the early
lag behavior for the variogram, ignoring the drift, or find a flat lying
where the drift component is not likely to have much of an effect on the
variogram. Have a look at the results -- does the valley still look like a
just like all normal valleys? Such a shape should be retained because for
a valley it makes sense.
>A further question (if anyone is still reading this), I want to accountfor the
>fact that the spatial variation over the valley surface is different inof the
>different dirrections (ie is anisotrpic) I want to krig in the direction
>long profile of the valley and in the direction of cross-section, can I dothis
>without accounting for the drift (mentioned above). Would accounting forthe
>anisotropy, cancel out the need to remove any drift that there might be inthe
>data as a result of glacier valleys not being flat?Anisotropies account for the different ranges in different directions.
are just that, trends -- an entirely different beast all together. You can
a drift in the cross-sectional direction, but still get more or less the
as the perpendicular direction.
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