# Quick script to determine whether the filename of each downloaded

# ASTER tile is faithful to its spatial location as specified in the

# GeoTIFF itself.

#

# This script is written to run on eos, based on the file system

# location of downloaded ASTER tiles as of 04-Aug-2011

#

# Jim Regetz

# NCEAS

# Created on 04-Aug-2011

library(rgdal)

# for a given file, return TRUE if file name matches the internally

# specified lower left corner, otherwise return string with those

# coordinates

check <- function(tilename, path=".", silent=TRUE) {

    # build expected filename

    origin <- round(GDALinfo(file.path(path, tilename),

        silent=silent)[c("ll.x", "ll.y")])

    ly <- origin["ll.y"]

    y <- sprintf("%s%02d", if (ly>=0) "N" else "S", abs(ly))

    lx <- origin["ll.x"]

    x <- sprintf("%s%03d", if (lx>=0) "E" else "W", abs(lx))

    expected.name <- paste("ASTGTM_", y, x, "_dem.tif", sep="")

    # compare to actual filename

    if (tilename==expected.name) {

        TRUE

    } else {

        paste(y, x)

    }

}

# produce vector of check results, with the actual file names as vector

# element names (takes ~12 minutes on eos)

aster.tiles <- list.files("~organisms/DEM/asterGdem",

    pattern="^ASTGTM.*_dem.tif$")

tilecheck <- sapply(aster.tiles, check)

# report mismatches

data.frame(expected=tilecheck[tilecheck!="TRUE"])

##                       expected

##ASTGTM_N59E069_dem.tif N63 E109

##ASTGTM_N63E113_dem.tif N69 E107

##ASTGTM_N63E117_dem.tif N69 E113

##ASTGTM_N64E098_dem.tif N70 E117

##ASTGTM_N65E104_dem.tif N73 E084

##ASTGTM_N65E111_dem.tif N73 E098

##ASTGTM_N65E117_dem.tif N66 E130