This works:
http://r-sig-geo.2731867.n2.nabble.com/file/n6890251/test.png
require(sp)
library(raster)
library(rgdal)
pixel <- 25000 #pixel dimension in meters for both x and y
xMin <- -3837500 #From NSIDC: ulxmap -3837500
xMax <- xMin + (pixel*304)
yMax <- 5837500 #From NSIDC: ulymap 5837500
yMin <- yMax - (pixel*448)
r <- raster(nrow=448, ncol=304, xmn=xMin, xmx=xMax, ymn=yMin, ymx=yMax)
projection(r) <- '+proj=stere +lat_0=90 +lat_ts=70 +lon_0=-45 +k=1 +x_0=0
+y_0=0 +a=6378273 +b=6356889.449 +units=m +no_defs'
#for(### Place time loop here){
yyyy<- "2011" ### Use for debugging
mm<- "10" ### Use for debugging
dd = 12 ### Use for debugging
##Near Real Time:
##
ftp://sidads.colorado.edu/pub/DATASETS/nsidc0081_nrt_nasateam_seaice/north/
##Best long-term record through 2010:
##
ftp://sidads.colorado.edu/pub/DATASETS/nsidc0081_nrt_nasateam_seaice/north/[yyyy]/
filename <-
paste("ftp://sidads.colorado.edu/pub/DATASETS/nsidc0081_nrt_nasateam_seaice/north/";,
"nt_",yyyy,mm,sprintf("%2.2d", dd),"_f17_nrt_n.bin", sep="")
con <- file(filename, 'rb')
x <- readBin(con, "raw", 300)
x <- readBin(con,"int", size=1, signed=FALSE, 150000)
close(con)
newx <- numeric(length(x)) #new variable for recoding the 'raw' byte
data
newx[x==251] <- 1 # arbitrarily set the the polar data hole to 100% ice
cover
newx[x>251] <- 0 # set all non-ice pixels to 0% ice cover
newx[x<251] <- x[x<251]/250 #scale ice cover to 1
r <- setValues(r, newx) # place result in raster
plot(r) # Plot it
#plot(land, add=T) #Plot a land map to for reference
sp <- as(r, 'SpatialGridDataFrame')
geoTiffFile<- paste('D:/NSIDC/NearRealTime/',
"nt_",yyyy,mm,sprintf("%2.2d", dd),'.tif',sep='')
writeGDAL(sp, geoTiffFile, drivername="GTiff")
#} ### end time loop
-----
Tony Fischbach, Wildlife Biologist
Walrus Research Program
Alaska Science Center
U.S. Geological Survey
4210 University Drive
Anchorage, AK 99508-4650
afischb...@usgs.gov
http://alaska.usgs.gov/science/biology/walrus
--
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