On 08/23/2017 04:20 PM, Even Rouault wrote:
On mercredi 23 août 2017 16:01:05 CEST Vincent Schut wrote:
> Hi all,
>
> I'm trying to get the /vsigzip/ driver working on srtm .hgt.gz files,
> but I don't succeed:
>
> gdalinfo /vsigzip/N37W105.hgt.gz
> ERROR 4: `/vsigzip/N37W105.hgt.gz' not recognized as a supported file
> format.
> gdalinfo failed - unable to open '/vsigzip/N37W105.hgt.gz'.
>
> This is with a .hgt.gz from here:
> https://s3.amazonaws.com/elevation-tiles-prod/skadi/N37/N37W105.hgt.gz
>
> gunzipping the file works OK.
>
> Any hints?
Fixed per https://trac.osgeo.org/gdal/ticket/7016
Thanks Even!
However opening time is really slow (which might be a problem or not
depending on what you're doing) as the whole file needs to be
downloaded and decompressed. The reason is that .hgt files are pure
raw data files without any header, so the only way to know the
dimensions is to check the file size against 3601*3601*2 bytes (SRTM 3
at low latitudes), 3601*1801*2 (SRTM 3 at high latitudes) or
1801*1801*2 (SRTM 1). But for a .gz file, the only way to get the
uncompressed file size is to uncompress it...
Even
--
Spatialys - Geospatial professional services
http://www.spatialys.com
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