[GRASS-user] srtm plus format and European bathymetry

[Michael Barton]

Thanks for the useful hints Maciej.

I tried to unzip (as the docs say) and found that they are not zipped. Then
I tried to follow the Russian-doll-like descriptions of 'these are formatted
like the previous releases' in the brief docs back to USGS EROS where I
could not find (yet) a decent description of the format.

I'll try your suggestions.

Michael


On 10/13/07 8:27 AM, "Maciej Sieczka" <tutey at o2.pl> wrote:

> Michael Barton wrote:
>> Ultimately, I'm trying to locate bathymetry off the coast of Europe to
>> create a DEM of Pleistocene Europe during times of low sea level (i.e.,
>> -300m). 
>> 
>> Following the FreeGIS.org link off the GRASS download data page, I found a
>> site with "STRM30 plus" that combine 1km SRTM with bathymetry
>> <ftp://topex.ucsd.edu/pub/srtm30_plus/data>. This seems just what I need.
>> However, I can't figure out the format or how to import it into GRASS. The
>> files show up like " w020n90.Bathmetry.srtm". I've tried r.in.gdal and
>> r.in.strm to no avail. I thought maybe the files were compressed and tried
>> to uncompress them without luck.
>> 
>> Can anyone suggest what to do with these files?
> 
> Michael,
> 
> ftp://topex.ucsd.edu/pub/srtm30_plus/README.V2.0.txt:
> 
> <snip>
> DATA FORMATS
> Data are provided as binary integers in exactly the same
> format as SRTM30.  The files must be uncompressed with gzip
> and are 16-bit big endian byte order.
> </snip>
> 
> Other than they don't seem gzipped actually, the information
> looks correct. These are 16 bit signed integer binary grids.
> 
> You can use r.in.bin, or r.in.gdal if you create appropriate
> header files (see r.in.srtm script for inspiration; note it
> cannot work with 30" SRTM data as it is now - currently it
> supports only 3" and 1" SRTM tiles). In the presence of
> properly formatted *.hdr GDAL supports such binary grids
> with "ESRI .hdr Labelled" driver [1]. In
> ftp://topex.ucsd.edu/pub/srtm30_plus/ermapper_headers there
> are ERmapper header files, which I suppose can be used to
> prepare their GDAL-understandable version.
> 
> [1] http://www.gdal.org/frmt_various.html#EHdr
> 
> Maciek

__________________________________________
Michael Barton, Professor of Anthropology
Director of Graduate Studies
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University

phone: 480-965-6213
fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton