[gdal-dev] MODIS reprojection

[Rutger]

Hey Laura,

Since the MxD14.A2 products are already projected in the sinusoidal
projection there is no need to warp using GCP's. Fitting a polynomial
through some GCP's will always be less accurate then using the projection
the data is already in.

Somewhere in the metadata in the HDF there should be a boundingbox (corner
coordinates, in sinusoidal projection) for the specific tile you are using,
you can then assign these with the projection using gdal_translate. Once
assigned, you can use gdalwarp in the same way as you already described.

Youre gdal_translate command should look somewhat like this:
gdal_translate -of "VRT" -a_srs "+proj=sinu +lon_0=0 +x_0=0 +y_0=0
+a=6371007.181 +b=6371007.181 +units=m +no_defs" -a_ullr 2223901.039333
-3335851.559000 3335851.559000 -4447802.078667 <input HDF subdataset>
<output vrt file>

You can get the correct subdataset reference by running gdalinfo on you HDF.
The coordinates i used are for tile h20v12, so make sure you use the ones
from your tile. I used a vrt as output which you can use as an input for
gdal_translate, but its also fine to use Geotiff or anything else you
prefer.

Hope this helps.

Regards,
Rutger










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