kriging: export to grid

Hello,

After kriging with the use of the  krige.conv function, I would like to 
export my result under the grid format. In order to view it into a GIS.

It was suggested to me to use the writeGDAL function into the rgdal package. 
However It looks like I have a problem of supported formats
(dataset object of SpatialGridDataFrame-class or SpatialPixelsDataFrame-class 
) that is not the same as the one resulting from my krige.conv function 
(kriging -class apparently)

I tried several function to achieve this conversion (getRasterData, 
SpatialGridDataFrame, SpatialPixelsDataFrame, create2GDAL, points2grid...). 
But without any success.

#my actual kriging script:
pred.grid = expand.grid(seq(170000, 130000, l = 50), seq(190000, 160000, l = 
50))
library(sp)
pred.grid$var3 <- 1
coordinates(pred.grid) <- c("Var1", "Var2")
gridded(pred.grid) <- TRUE

# Create a SpatialPixelsDataFrame or SpatialGridDataFrame object first
# - forced here by including a non-coordnate column to the data frame
myPred = krige.conv(myGData, loc = pred.grid, krige = krige.control(obj.m = 
myOLSMod))
myPred = krige.conv(myGData, loc = coordinates(pred.grid),
  krige = krige.control(obj.m = myOLSMod))

# Krige with the coordinates of the object

pred.grid$predict <- myPred$predict

# add the predictions (and standard errors if you like) to the
# object, they are in the correct order;
# then write out, choosing the output column as desired

tf <- tempfile()
writeGDAL(pred.grid["predict"], tf, drivername="GTiff") # not type="Byte"!
GDALinfo(tf)

# I suppose you are using the temporary file here to test your approach
# as you ought to put the output file in a permanent place if you will
# need it later

Hope this helps,

Roger
image(myPred, loc = pred.grid, col = gray(seq(1, 0.1, l = 30)))

#my conversion attempts
tf <- tempfile()
writeGDAL(myPred, tf, drivername="GTiff", type="Byte", options=NULL)
[Erreur dans function (classes, fdef, mtable) : unable to find an inherited 
method for function "gridded", for signature "kriging"]

Thanks a lot,

Nicolas

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Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no

kriging: export to grid

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