[Gdal-dev] Warping image...

[Markus Neteler]

On Mon, Sep 10, 2007 at 11:45:28PM +0200, Mario Cavicchi wrote:
> Hi all,
> I have a little problem with a modis image, i must to reproject it in UTM 
> meter. I use the function GDALCreateWarpOperation and i must to set nOrder 
> = 3. The output image is correct, but the left and right sides are wrong.
> I don't able to explain where is the problem, but the result is this
> http://members.ferrara.linux.it/cavicchi/tmp/modis.jpg

Mario,

I don't think that it is a good idea to use 3rd order
polynomial to warp MODIS. The effect which you see looks
pretty much as an overshoot. I had the same issue with
AVHRR using 3rd order polynomials, see
  http://mpa.itc.it/markus/avhrr/
  ->  irectify_3rd_order_avhrr.png
      (the use code is rather identical to the GDAL code)

Is the original a MODIS HDF in Sinusoidal projection?

I have written a script to reproject MODIS to LatLong/WGS84:
http://mpa.itc.it/markus/useful/modis_hdf2erdas_ll_wgs84.sh

You can adapt the script easily to write out UTM but
it is recommended to extract only a spatial subset
since a UTM zone is smaller than a full MODIS scene
(if I recall correctly).

ciao
Markus

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ITC -> dall'1 marzo 2007 Fondazione Bruno Kessler
ITC -> since 1 March 2007 Fondazione Bruno Kessler
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