[Gdal-dev] Re: GDAL SRTM hgt code

[WolfgangZ]

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