[Gdal-dev] warping MODIS data with gdal

[Markus Neteler]

On Wed, Nov 29, 2006 at 02:08:16PM +0300, Andrey Kiselev wrote:
> On Tue, Nov 28, 2006 at 05:16:06PM +0100, Markus Neteler wrote:
> > MODIS does not use the "Normal Sphere (r=6370997) but 6371007.181
> > I got this from:
> >  http://edcdaac.usgs.gov/landdaac/tools/mrtswath/info/ReleaseNotes.pdf
> 
> GDAL fetches the sphere parameter just fine. For above file I have:
> 
> $ gdalinfo -nomd HDF4_EOS:EOS_GRID:"MOD09A1.A2001289.h08v05.004.2003162200605.hdf":MOD_Grid_500m_Surface_Reflectance:sur_refl_b01
> Driver: HDF4Image/HDF4 Dataset
> Size is 2400, 2400
> Coordinate System is:
> PROJCS["unnamed",
>     GEOGCS["Unknown datum based upon the custom spheroid",
>         DATUM["Not specified (based on custom spheroid)",
>             SPHEROID["Custom spheroid",6371007.181,0]],
>         PRIMEM["Greenwich",0],
>         UNIT["degree",0.0174532925199433]],
>     PROJECTION["Sinusoidal"],
>     PARAMETER["longitude_of_center",0],
>     PARAMETER["false_easting",0],
>     PARAMETER["false_northing",0],
>     UNIT["Meter",1]]
> Origin = (-11119505.196667000651360,4447802.078666999936104)
> Pixel Size = (463.312716527917246,-463.312716527916677)
> Corner Coordinates:
> Upper Left  (-11119505.197, 4447802.079) (130d32'26.62"W, 40d 0'0.00"N)
> Lower Left  (-11119505.197, 3335851.559) (115d28'12.19"W, 30d 0'0.00"N)
> Upper Right (-10007554.677, 4447802.079) (117d29'11.96"W, 40d 0'0.00"N)
> Lower Right (-10007554.677, 3335851.559) (103d55'22.97"W, 30d 0'0.00"N)
> Center      (-10563529.937, 3891826.819) (115d58'24.91"W, 35d 0'0.00"N)
> Band 1 Block=2400x1 Type=Int16, ColorInterp=Gray
> 
> > I found some dirty trick to tell GDAL about it, see my script at:
> > http://mpa.itc.it/markus/useful/modis_hdf2erdas_ll_wgs84.sh
> 
> That looks strange for me. The script overrides sphere parameter in
> output file, does it mean that after gdalwarp output file has incorrect
> sphere? Or it means that gdalwarp actually warps to WGS84 ellipsoid
> instead of normal sphere specified in PROJ.4 string? I am not sure that
> the problem is in HDF driver here.

Hi Andrey,

I also suspect a problem in gdalwarp rather than the HDF driver.

My bugtracker report contains a link to MODIS for testing which seems to
become shifted if I use the standard gdalwarp procedure while
it works with sphere parameter overriding.

Best regards,
Markus