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### Script to download and process the MOD44W water mask from the USGS
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setwd("/home/adamw/acrobates/Global/land")
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url="http://e4ftl01.cr.usgs.gov/MOLT/MOD44W.005/2000.02.24/"
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### download the 250m land tiles
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system(paste("wget -np -nd --no-clobber -r ",url," -P tiles -R html -A hdf"))
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## modis projection
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mproj="+proj=sinu +lon_0=0 +x_0=0 +y_0=0 +a=6371007.181 +b=6371007.181 +units=m +no_defs"
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## destination projection
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dproj="+proj=cea +ellps=WGS84 +lat_ts=30"
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### Get list of tiles
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files=list.files("tiles",recursive=T,full=T)
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maskfiles=paste("HDF4_EOS:EOS_GRID:\"",files,"\":MOD44W_250m_GRID:water_mask",sep="")
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## write out a table of files to process into VRT
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write.table(maskfiles,file="tiles.txt",row.names=F,col.names=F,quote=F)
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## how many are there?
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length(files)
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## check them out
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system(paste("gdalinfo ",files[1]))
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system(paste("gdalinfo ",maskfiles[1]))
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## test conversion of one tile
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system(paste("gdalwarp -overwrite -multi -s_srs \"",mproj,"\" -t_srs \"",dproj,"\" -co COMPRESS=LZW -r near ",maskfiles[307]," land_behrmann.tif"))
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### create VRT
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system(paste("gdalbuildvrt -overwrite -input_file_list tiles.txt land.vrt"))
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system(paste("gdalwarp -overwrite -multi -s_srs \"",mproj,"\" -t_srs \"",dproj,"\" -of GTiff -co COMPRESS=LZW land.vrt land.tif"))
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## mosaic directly from tiles to tif
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system(paste("gdal_merge.py -of GTiff -co COMPRESS=LZW -o land.tif ",paste(maskfiles,collapse=" ")))
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system(paste("gdalwarp -overwrite -multi -s_srs \"",mproj,"\" -t_srs \"",dproj,"\" -of vrt -r near land.vrt land_behrmann.vrt"))
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system(paste("gdal_translate -of GTiff -co COMPRESS=LZW land_behrmann.vrt land_behrmann.tif"))
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system("gdalinfo land_behrmann.vrt")
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