Script to correct the vertical mirror error of ASC files exported from QGIS through the "Raster->Conversion->Translate" command (which in turn invokes gdal_translate)

qgis_asc_unmirror.sh

#!/bin/bash
#
# corrects the vertical mirror error of ASC files exported from QGIS
# through the "Raster->Conversion->Translate" command
# (which in turn invokes gdal_translate)
#
# RafDouglas - 190505
#
#
# example header section of the ASC file:
#
#ncols        600
#nrows        300
#xllcorner    565200.000000000000
#yllcorner    4797400.000000000000
#cellsize     10.000000000000
#NODATA_value  0

if [ -z $1 ]; then

	echo "Usage: $0 input_file.asc"
	exit
fi

if [ ! -e $1 ]; then

	echo "Usage: $0 input_file.asc"
	echo "The specified input file ($1) does not exist."
	exit
fi

mypid=$$

mytmp_file='temp_'"$mypid"'.asc'
mytmp_prj='temp_'"$mypid"'.prj'

infile=$1
inprj=$(echo $infile|sed 's/.asc/.prj/g')

outfile=$(echo $infile|sed 's/.asc/_proper.asc/g')
outprj=$(echo $infile|sed 's/.asc/_proper.prj/g')


head -6 "$infile"|awk '{h[$1]=$2}END{
yllcorner_proper=h["yllcorner"]+h["nrows"]*h["cellsize"]
print "ncols        " h["ncols"]
print "nrows        " h["nrows"]
print "xllcorner    " h["xllcorner"]
#print "yllcorner    " h["yllcorner"]
print "yllcorner    " yllcorner_proper
print "cellsize     " h["cellsize"]
print "NODATA_value " h["NODATA_value"]
}' > "$mytmp_file"

#add the data rows in reversed order 
tail -n+7 "$infile"|tac >> "$mytmp_file"

if [ ! -e $outfile ]; then
	mv -n "$mytmp_file" "$outfile"
	cp -n "$inprj" "$outprj"
	echo
	echo "Output file: $outfile is ready"
else
	cp -n "$inprj" "$mytmp_prj"
	echo
	echo "Waring: $outfile is already present. Not overwriting it."
	echo "Output file: $mytmp_file is ready"
fi

echo