[mkgmap-dev] DEM-file generation from geo-tiff sources ?

Sun Jan 7 08:26:48 GMT 2018

Hi Frank,
so these are the steps I used on my ubuntu machine:

1. Download the Copernicus Data and unzip
2. create the virtual tif-image gdalbuildvrt all.vrt *.TIF 
3. cut the 1°x1° tiles with the perl script
this results in almost 65GB of uncompressed tif tiles

4. convert every tif-tile to hgt using the following loop

for i in N*.tif ; do
gdal_translate -strict -q -eco -of SRTMHGT $i hgt/`basename $i tif`hgt ;
done ;
rm -f *.hgt.aux.xml ;

5. I found out that the file N27W000.hgt is completely empty, so all tiles
with the identical content are empty also.
with the following commands I removed the empty tiles

mv N27W000.hgt EMPTY.hgt;
for i in N*.hgt ; do
	if diff EMPTY.hgt $i ; then 
		rm -f $i;
	fi
done ;
rm -F EMPTY.hgt;

Now I got 25GB in 1001 hgt tiles

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