[Gdal-dev] Re: GDAL SRTM hgt code

[Even Rouault]

Hi,

A specific driver for SRTM hgt files has been added a few weeks ago to GDAL 
trunk (future 1.5.0). You may test it with nightly snapshot or latest 
FWTools-2.0.0


Le Thursday 15 November 2007 20:14:34 Rick Niles, vous avez écrit :
> Since SRTM hgt-files is the best public available terrain data around
> (that I know of..), it seems like it's worth it to have a specific
> front-end to handle it directly via GDALOpen().  I can see why some
> would argue that's just a special case of a raw 2-byte file, but I don't
> think it would be ugly to have a specific filter to handle this
> extremely popular data.  There's 3-second and 1-second SRTM data and I'm
> not sure you can auto-detect which is which.
>
> What do you think?
>
> Rick Niles.
>
> WolfgangZ wrote:
> > list67 at netscape.net schrieb:
> >> Has anyone added code to GDAL so that a SRTM (1 or 3 arcsecond) hgt
> >> file can be passed to GDALOpen(...) for use?
> >>
> >> I did some searching and noticed that there are some format
> >> conversion workarounds for using the SRTM files with GDAL, but I
> >> didn't find any info about wether or not a more direct open
> >> capability had been implemented?
> >>
> >> Thank you.
> >>
> >>    Mike
> >
> > hi Mike,
> >
> > you can have a look at the grass r.in.srtm script. It basically unzips
> > and renames the file to .bil and furthermore you need to create a
> > textfile with the same file name and the fiel ending .hdr with the
> > following content:
> > For 3arcsec data:
> >     BYTEORDER M
> >     LAYOUT BIL
> >     NROWS 1201
> >     NCOLS 1201
> >     NBANDS 1
> >     NBITS 16
> >     BANDROWBYTES 2402
> >     TOTALROWBYTES 2402
> >     BANDGAPBYTES 0
> >     NODATA -32768
> >     ULXMAP $ULXMAP
> >     ULYMAP $ULYMAP
> >     XDIM 0.000833333333333
> >     YDIM 0.000833333333333
> >
> > of for 1arcsec data:
> >     BYTEORDER M
> >     LAYOUT BIL
> >     NROWS 3601
> >     NCOLS 3601
> >     NBANDS 1
> >     NBITS 16
> >     BANDROWBYTES 7202
> >     TOTALROWBYTES 7202
> >     BANDGAPBYTES 0
> >     NODATA -32768
> >     ULXMAP $ULXMAP
> >     ULYMAP $ULYMAP
> >     XDIM 0.000277777777777778
> >     YDIM 0.000277777777777778
> >
> > You need to replace $ULXMAP and $ULYMAP with the upper left
> > coordinates of that tile. As s_srs you can use EPSG:4326.
> >
> > Greetings
> > Wolfgang
> >
> >
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