[GRASS-user] v.surf.rst and null values

[Dylan Beaudette]

On Monday 03 March 2008, jessica.gervais at tudor.lu wrote:
> Dear all,
>
> I have a set of data points in a semi-column separated file(example file :
> test.txt)
> For each location, I have meteo data have been recorded.
> Missing values are represented by represented by blank.
> I am using v.in.ascii to import these points.
> Then, I want to interpolate these point data with v.surf.rst.
> The interpolation should use only points where there data was recorded,
> e.g. to skip points were there is missing value.
> But v.surf.rst threat the missing values as is they were "0".
>
> Do anyone know how to specify to the v.surf.rst function that blank values
> are null values ?
> Or maybe I should define these point as null values when I import the
> points with v.in.ascii ?
>
> Many thanks in advance,
>
> Jessica
>
> Thanks in advance

The trick is to get v.in.ascii to respect any NODATA conventions that are used 
in your input file.

attached is a simple file that contains a NODATA entry, and is read correctly 
by v.in.ascii.

Optionally, you can use the 'where' operator for v.surf.rst to pre-filter your 
points.

Cheers,
Dylan

-- 
Dylan Beaudette
Soil Resource Laboratory
http://casoilresource.lawr.ucdavis.edu/
University of California at Davis
530.754.7341
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