[GRASS-user] Interpolation method for parallel samples

[Martin Album Ytre-Eide]

Thanks for your answer Markus! 

Here are my thoughts and trials: 

The normal screen output when running v.surf.bspline looks something like this:

Reading values from attribute table...
Initializing output...
 100%
Load masking map
 100%
Processing subregion 1 of 25...
  90%

##
..but when running with  ew_step=50 and ns_step=1000, I get:

Reading values from attribute table...
Initializing output...
 100%
Load masking map
 100%
 100%
 100%
 100%
  10%

... and it does not seem to finish at any point.

Even setting the ew_step=90 generates the same behaviour.

My result with 100 and 1000 is not that bad actually - I might say I'm happy with that.

 I am experimenting with v.surf.rst, but for some reason it ignores a lot of points (to dence). I also don't know if I understand the theta and scalex parameters. For me, it seems they are optimizing the results from a "feature" that is anisotropic. Does this "feature" in my case mean my area with samples that I wont to interpolate? My area is somewhat rectangular - being about twice the size in the nort-south direction, but my data - as I mentioned , are spaced by 50 m in the e-w direction and 1000 m in the n-s directions. So what combo of theta and scalex should I use?

Thanks!

Martin

_______________________________________
Fra: Markus Metz [markus.metz.giswork at gmail.com]
Sendt: 17. desember 2014 22:11
Til: Martin Album Ytre-Eide
Kopi: grass-user at lists.osgeo.org
Emne: Re: [GRASS-user] Interpolation method for parallel samples

Martin Album Ytre-Eide wrote:
> Hello!
>
> I have airborne gamma measurements obtain in lines. The spatial distance
> between the 'points' along the line is 50m (e-w direction) and the spatial
> distance between the lines is 1000m (n-s direction)
>
> I am currently experimenting with the v.surf.bspline function - setting
> ew_step=100 and ns_step=1000. I am having trouble setting the ew_step any
> lower.....?

What exactly is the trouble with setting ew_step any lower? In theory,
it should be possible to set ew_step to any value.

Markus M

> I am also using the smoothing parameter lambda_i.
>
> If anyone have some interpolation tips with this type of data - I would be
> happy to hear about it.
>
>
>
> Martin
>
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