[GRASS-user] TRMM (3B43) handling

[Markus Metz]

On Sun, Nov 14, 2010 at 8:41 PM, Markus Neteler <neteler at osgeo.org> wrote:
> On Sun, Nov 14, 2010 at 7:42 PM, nikos <vesnikos at gmail.com> wrote:
>> On Sun, 2010-11-14 at 16:35 +0100, Markus Neteler wrote:
>>> On Sun, Nov 14, 2010 at 4:01 PM, nikos <vesnikos at gmail.com> 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