[GRASS-user] cross validation v.surf.rst

[Anna Petrášová]

Hi,

On Tue, Nov 4, 2014 at 3:58 AM, Ivan Marchesini <ivan.marchesini at gmail.com>
wrote:

> Hi,
> I'm using the cross validation procedure of v.surf.rst
>
> I have around 250 points on a region of 100 square kilometers and I'm
> working in a region having 10 meters resolution
>
> When I run a cross validation using v.surf.rst I regularly get the cvdev
> file but what it seems strange is that it takes only few seconds to run
> on a normal PC with a i7 core.
>
> I suppose that it would had to run the interpolation 250 times but it
> seems it runs only one time.
>
> Is this normal?
>

Yes, first, you have only 250 points, that's not too many. Then during the
cross validation, only the value in the particular point is computed, not
in every cell of the raster. If you would use a recent version (couple of
weeks ago) of grass 7, there should be even some speedup in storing
attribute values in database.

Best,
Anna

>
> many thanks
>
> Ivan
>
>
>
>
>
>
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