[GRASSLIST:9957] Re: R, kriging and grass6

[ivan marchesini]

Dear Roger...
thank you for your previous answer... 
can you fast describe me how to create a SpatialGrid object starting
from the data returned from Gmeta6()???
only few hints...  :-)
I only need this to perform the kriging process, because I have already
generated the variogram and I only need the grid over which to perform
the prediction.....
thank you very much...
ivan


Il giorno lun, 23/01/2006 alle 13.14 +0100, Roger Bivand ha scritto:
> On Mon, 23 Jan 2006, ivan marchesini wrote:
> 
> > Hi to all...
> > we are triyng to use kriging using R and grass6,
> > We have seen a lot of documentation about R and GRASS5 but not so many
> > about grass6...
> > the problem is that we are trying to do an interpolation using the
> > functions gmeta6 and kriging...
> > if we are not wrong, the R library GRASS is developed for grass5 and
> > inside there is the function krige.G that use the location data acquired
> > using the gmeta() function...
> > the problem is that we have found the gmeta6() function but not the
> > krige.G6 function and obvously the krige.G doesn't work using the
> > location data of grass6 (obtained using gmeta6)  
> > 
> > how can we simply solve this problem....
> 
> krige.G was a nasty hack, and should best be forgotten. The direct route 
> is to use the sp classes in R and implemented for GRASS in spgrass6 - see 
> GRASS News for the GRASS side and R News for the R side, combined with a 
> proper R geostats package. Of those available, gstat is tightly bound to 
> sp classes, so as far as I know, the only bit that needs doing by hand is 
> to create a GridTopology object, or a SpatialGrid object, from the data 
> returned by gmeta6() to pass to the kriging prediction function.
> 
> If you like, we can iterate to a working example from passing the vector 
> points to R from GRASS, doing the modelling and kriging predictions, and 
> passing the prediction rasters back to GRASS, but I'd like input from 
> users to make the description sound.
> 
> Best wishes,
> 
> Roger
> 
> > 
> > thank you
> > 
> > Ivan
> > 
> > 
> > 
> > 
> 
-- 
Ivan Marchesini
Department of Civil and Environmental Engineering
University of Perugia
Via G. Duranti 93/a 
06125
Perugia (Italy)
e-mail: marchesini at unipg.it
        ivan.marchesini at gmail.com
tel: +39(0)755853760
fax: +39(0)755853756