[Gdal-dev] SRTM data and GDAL

Vincent Schut schut at sarvision.com
Thu Jul 3 08:49:43 EDT 2003


Sorry, lept behind...
GDAL seems already able to read the SRTM files I downloaded, apparently. 
gdalinfo shows the right coordinates, at leas, etcetera.

Cheers,
Vincent.

On Thursday 03 July 2003 11:48, Vincent Schut wrote:
> Dear GDAL developers & users,
>
> any news on a more sophisticated/automagicated way to open/convert SRTM
> data now South America is publicly available too?
>
> Cheers,
> Vincent.
>
> On Friday 07 March 2003 10:43, Markus Neteler wrote:
> > Dear GDAL users,
> >
> > since yesterday a SRTM shuttle elevation data are available
> > for Northern America at around 90m resolution (0:00:03 deg):
> >
> > http://www.jpl.nasa.gov/srtm/cbanddataproducts.html
> > ftp://srtm.usgs.gov/pub/data/srtm/North_America/3arcsec/
> >
> > The trick to use them with GDAL is as follows:
> >
> > - unpack the .zip file
> > - mv NXXWYYY.hgt NXXWYYY.bil
> > - create a .hdr file (ARC/INFO style) from the file name:
> >
> > Example for N18W077.bil
> >
> > BYTEORDER     M
> > LAYOUT        BIL
> > NROWS         1201
> > NCOLS         1201
> > NBANDS        1
> > NBITS         16
> > BANDROWBYTES  2402
> > TOTALROWBYTES 2402
> > BANDGAPBYTES  0
> > NODATA        -32768
> > ULXMAP        -76.9995833333        <- WYYY - 0.0004166667
> > ULYMAP        19.00041666666667     <- NXX  + 1.0004166667
> > XDIM          0.000833333333333
> > YDIM          0.000833333333333
> >
> >
> > Then gdalinfo then accepts the file and reports:
> >
> > gdalinfo -mm N18W077.bil
> > Driver: EHdr/ESRI .hdr Labelled
> > Size is 1201, 1201
> > Coordinate System is '
> > Origin = (-77.000000,19.000833)
> > Pixel Size = (0.000833,-0.000833)
> > Corner Coordinates:
> > Upper Left  ( -77.0000000,  19.0008333)
> > Lower Left  ( -77.0000000,  18.0000000)
> > Upper Right ( -75.9991667,  19.0008333)
> > Lower Right ( -75.9991667,  18.0000000)
> > Center      ( -76.4995833,  18.5004167)
> > Band 1 Block=1201x1 Type=Int16, ColorInterp=Undefined
> >     Computed Min/Max=-10.000,2024.000
> >   NoData Value=-32768
> >
> > Maybe the GDAL authors could add a simple HGT driver which
> > automagically constructs the .hdr file internally on the fly.
> >
> > Anyway, with above method you can easily import/convert
> > the data (also tested with GRASS).
> >
> > Cheers
> >
> >  Markus

-- 
______________________________________
Vincent Schut
Sarvision B.V.
Wageningen, The Netherlands
www.sarvision.com



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