[GRASS-user] Creating location for direct import of Smith & Sandwell topo data, GMT

Hamish hamish_b at yahoo.com
Sat Apr 26 22:10:21 EDT 2008


I have been trying to figure out how to create a GRASS location for the
native projection of Smith and Sandwell's 1-minute global elevation
v9.1b, August 21, 2007.  http://topex.ucsd.edu/marine_topo/mar_topo.html 
(dataset is 712mb uncompressed)

Data is given as simple Mercator on a sphere, the same as GMT's "img2grd
-D". I wish to eventually corellate with or reproject into WGS84 lat/lon,
but to minimize loss of information I prefer to work with the original
data as long as possible.

I have a working method using img2grd; g.region; grd2xyz | r.in.xyz.
Although I am still a bit unsure about the north-south resolution, it all
seems to line up well with a world coastline vector overlay.

img2grd -> grdreformat =bf to convert into an old GMT native file which
r.in.bin's -h flag knows about seems to harm the data.

more notes and ideas about it here:

has anyone solved this before? eventually I would like the clean up the
above wiki page with a clear mini-howto for using this data with GRASS.


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