hey list, Sorry that I took so much to respond,
I'm orientating in a different direction right now, and I'd like an opinion (on TRMM 3B43 ofc). Here are my thoughts: a) the hdf that delivers the product only wraps a table 1400 long x 440 tall. Each tile is represented by known cords. eg the upper left tile ( [0][0] ) have the coords of -180deg, 50deg. This is a fact. And also it is a fact the dArc from each tile to another tile (horizontally and vertically) its 0.25arcs. b) So we can controllably somehow "dump" the data into a csv of x,y z where z are mm/hr (3b43 specification). x,y in a φ,λ coordinate system (reprojections and projections are not my strong point). results are 1440 x 400 points with known known coords and values. c) interpolate for the area you're interested for. d) You got yourself a raster to have fun with. Taken into account the reprojection from φ,λ is possible and a viable solution, the hard part seems to be getting the data. Here's my solution on that: Giovanni Interface so kindly provided by nasa.gov . You get the data in ascii format for the area you're researching for and free to work with htem. Here's an example on data dump: http://disc2.nascom.nasa.gov/daac-bin/Giovanni/tovas/Giovanni_cgi.pl?west=16.0&north=43.0&east=30.0&south=31.0¶ms=1|3B43_V6&plot_type=Area+Plot&byr=2006&bmo=05&eyr=2006&emo=05&begin_date=1998/01&end_date=2010/10&cbar=cdyn&cmin=&cmax=&yaxis=ydyn&ymin=&ymax=&yint=&ascres=0.25x0.25&global_cfg=tovas.global.cfg.pl&instance_id=TRMM_V6&prod_id=3B43&action=ASCII+Output My thoughts are that a python script that utilities the above method is possible. Any thoughts on my comments would be really appreciated. Best Regards, Nick Ves On Mon, 2010-11-15 at 11:03 +0100, Markus Metz wrote: > On Sun, Nov 14, 2010 at 8:41 PM, Markus Neteler <[email protected]> wrote: > > On Sun, Nov 14, 2010 at 7:42 PM, nikos <[email protected]> wrote: > >> On Sun, 2010-11-14 at 16:35 +0100, Markus Neteler wrote: > >>> On Sun, Nov 14, 2010 at 4:01 PM, nikos <[email protected]> wrote: > >>> > > >>> > > >>> > I'm battling to import the 43b3 Product (TRMM perspiration + other > >>> > >>> (http://disc.sci.gsfc.nasa.gov/precipitation/documentation/TRMM_README/TRMM_3B42_readme.shtml) > > You could also use the TRMM tools [1] to dump the data to a raw binary > file. Last time I did that I noted that the binary file is rotated by > 90°, i.e. north is right and west is up (or north is left and west is > down, forgot the rotation direction). > > >> > >> I tried > >> > >> ./gdal_translate -a_ullr -180 50 -50 180 > >> HDF4_SDS:UNKNOWN:"/DIR/OF/TRMM_IMAGE/3B43.060801.6.HDF":1 test.tif > >> > >> which makes an interesting tif, that is not empty, but when I load it > >> with qgis (use psedocolor) its square(?). The image should have a > >> 1440/400 ratio. > > What does > gdalinfo HDF4_SDS:UNKNOWN:"/DIR/OF/TRMM_IMAGE/3B43.060801.6.HDF":1 > say? There should be 400 rows and 1440 columns, and not vice versa, > 1440 rows and 400 columns (suspected 90° rotation mentioned above). > > > > > Wait - AFAIK you need to use "gdalwarp" on it, not gdal_translate. > > > > Hm, there is no coordinate system specified in the hdf, so gdalwarp > would only work with -s_srs wgs84 -t_srs <something else than wgs84>. > Or translate first, add gcps during translation, then warp? > > Markus M > > [1] > ftp://disc2.nascom.nasa.gov/software/trmm_software/Read_HDF/READTRMM_V2.tar _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
