[gdal-dev] Dealing with SRTM! v3 files

[Even Rouault]

On samedi 18 avril 2020 17:01:43 CEST Carlos Dávila wrote:
> Hello all
> 
> I want to process SRTM1 data from Earthexplorer using mkgmap
> <http://www.mkgmap.org.uk/>, an open source software to build Garmin
> maps from OpenStreetMap data. Currently, earthexplorer serves SRTM1 data
> as *.tiff files of 3601x3601x2=24,7 MB, but also as files of half that
> size. I use gdal to convert *.tiff to *.hgt, as mkgmap is not able to
> read *.tiff.
> 
> These smaller files seem to contain the same information and gdal is
> able to convert them to *.hgt files without problems, in the same way
> than standard size ones, but mkgmap fails to read the small hgt files.
> Given gdal "understands" these small srtm files, could you give me some
> clue on how it is done, so that developers of mkgmap can add this
> capability?

The file with half size have probably width=1801 at higher latitudes (60deg I believe)

GDAL SRTMHGT driver source code at
https://github.com/OSGeo/gdal/blob/master/gdal/frmts/srtmhgt/srtmhgtdataset.cpp

-- 
Spatialys - Geospatial professional services
http://www.spatialys.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/gdal-dev/attachments/20200419/4c7f48d5/attachment-0001.html>