[GRASS-user] Interpolate grid(s) based on vector.

Hamish hamish_b at yahoo.com
Thu Aug 1 18:24:56 PDT 2013

Hi Bob,

> I have a set of rasters (ground acceleration, modal mag., and
> distance) that I want to interpolate based on the location of
> my point features (borehole location) and update my point feature
> with the values from this interpolation.  I see that v.what.rast
> might help, but I'm not sure what kind of interpolation it uses
> (probably nearest neighbor?).  I also see that v.sample can be
> used, but it does not work with geographic coordinate system locations.
> So, I was hoping that the list might have other ideas in solving my problem.

I think it is best to approach the problem in two steps. First
do your interpolations using a method appropriate to your data type,
sampling density, sensitivity to outliers, etc.
Then once you have your interpolated surface run v.what.rast, or
v.rast.stats, or from addons v.rast.stats2 or v.what.rast.buffer
depending if you want to pick off the exact interpolated value
at a given site, a statistical indicator for values around that
site (e.g. variance) as either a buffer distance or within a
given vector polygon.

By the way, we are currently discussing / upgrading the v.krige
offerings, you're most welcome to weigh in on the conversation
if that's what you're after.


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