HI Gerd I don't think conversion is wrong. If input geotiff file is 24MB, output hgt file is 24 MB, if input tiff is 12MB, output hgt is 12MB I use this command on Linux: for i in *.tif ; do gdal_translate -strict -q -eco -of SRTMHGT $i `basename $i tif`hgt ; done ; rm -f *.hgt.aux.xml BTW, gdal is also able to deal with small SRTM files El 16/4/20 a las 11:31, Gerd Petermann escribió:
Hi Carlos,
so your conversion routine is wrong. The file size is 12.970.802 bytes. There is no integer n for which 2 * n^2 results in this value.
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Carlos Dávila <cdavilam@orangecorreo.es> Gesendet: Donnerstag, 16. April 2020 11:19 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] "Small" SRTM1 files and DEM maps
Hi Gerd Forgot to mention files are downloaded as geotiff, but I then convert them to hgt, sorry. You can download a sample one from https://alternativaslibres.org/tmp/N50E118.hgt
El 16/4/20 a las 9:18, Gerd Petermann escribió:
Hi Carlos,
are you talking about geotiff format? I think someone documented how that format can be converted to *.hgt. Can you post a link to such a file?
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Carlos Dávila <cdavilam@orangecorreo.es> Gesendet: Montag, 13. April 2020 14:08 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] "Small" SRTM1 files and DEM maps
Hi Gerd They are downloaded by phyghtmap. This is what I found digging into phyghtmap files: |def getSRTMFileServer(self, resolution, srtmVersion):|| || if srtmVersion == 2.1:|| || return "https://dds.cr.usgs.gov/srtm/version2_1/SRTM{0:d}".format(resolution)|| || elif srtmVersion == 3.0:|| || if resolution == 1:|| || urlRe = "https://earthexplorer.usgs.gov/download/8360/SRTM1{:s}V3/GEOTIFF/EE"|| || elif resolution == 3:|| || urlRe = "https://earthexplorer.usgs.gov/download/4960/SRTM3{:s}V2/GEOTIFF3/EE"|| || return urlRe| They should come from the second URL above.
El 13/4/20 a las 8:24, Gerd Petermann escribió:
Hi Carlos,
sorry for the late response. I found no hint on the phyghtmap page http://katze.tfiu.de/projects/phyghtmap/ regarding a new format for srtm data. The hgt format is not compressed. Do you know from where these 12.4 MB files came from?
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Carlos Dávila <cdavilam@orangecorreo.es> Gesendet: Samstag, 11. April 2020 17:09 An: Development list for mkgmap Betreff: [mkgmap-dev] "Small" SRTM1 files and DEM maps
I use phyghtmap to build contour lines and also to download hgt data that I then use to build DEM maps with mkgmap. For a long time, SRTM1 files (and also VFP1) have all been ~24.7 MB in size, but lately (I don't remember since when) SRTM1 are also served as 12.4 MB files. phyghtmap is able to generate contour lines from those small files, as they seem to contain the same information but with a different compression ratio, but mkgmap fails to read them, and report them as missing. Would it be possible to get support for such files in mkgmap? _______________________________________________ mkgmap-dev mailing list mkgmap-dev@lists.mkgmap.org.uk http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev _______________________________________________
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