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

GRASS GRASS user
1

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
_________________________________________

Jessica Gervais
Tel: +352- 425991-628
Mail: jessica.gervais@tudor.lu

Resource Centre for Environmental Technologies,
Public Research Centre Henri Tudor,
Technoport Schlassgoart,
66 rue de Luxembourg,
P.O. BOX 144,
L-4002 Esch-sur-Alzette, Luxembourg
(See attached file: test.txt)

(attachments)

test.txt (29 Bytes)

2

On Monday 03 March 2008, jessica.gervais@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

(attachments)

test.txt (115 Bytes)