hi all,
excuse me for not giving up. i undertook some additional tests, and i got the same problems i described below. But i can't believe that nobody is working with gdal and modis level 1b data. At least this format is listet as supported at http://www.gdal.org/frmt_hdf4.html.
So my question: does anybody in this list work with modis level 1b? If yes, is the georeference of the resulting image ok or does somebody knows an workaround?
maybe the answer is, that it is not possible to warp modis level 1b data with gdal because the modis geolocation (mod3xxx) file is missing?
i appreciate any help.
cheers
anna
Von: "Chaitanya kumar CH" <[email protected]>
Gesendet: 19.01.2011 10:13:49
An: "anna auge" <[email protected]>
Betreff: Re: [gdal-dev] Modis L1B SWATH: georef problem hdf to geotiff
Anna,
Check a couple of GCPs to rule out bad data. If they are OK, file a ticket at http://trac.osgeo.org/gdal/newticket
On Wed, Jan 19, 2011 at 1:23 PM, anna auge <[email protected]> wrote:
So it is a problem with gdalwarp and the GCPs ín the GeoTiff. Do you have any hints how to go on with this problem?Cheers, Anna
Von: "Nikolaos Hatzopoulos" <[email protected]>
Gesendet: 19.01.2011 01:33:43
An: "anna auge" <[email protected]>
Betreff: Re: [gdal-dev] Modis L1B SWATH: georef problem hdf to geotiff
You are right, I notice that there isn't any difference from the
band_1.tiff and band_1_warp.tiff
--Nikos Hatzopoulos
On Mon, Jan 17, 2011 at 8:15 AM, anna auge <[email protected]> wrote:
Hi all,
I am trying to convert modis level 1B data (type SWATH) to geotiff following these steps.
1) Examining the HDF
gdalinfo d:\modis\1b\MOD021KM.A2011008.0850.005.2011008195744.hdf
gdalinfo HDF4_EOS:EOS_SWATH:"d:\modis\1b\MOD021KM.A2011008.0850.005.2011008195744.hdf":MODIS_SWATH_Type_L1B:EV_1KM_RefSB
2) Extracting the 1. band of the subdataset MODIS_SWATH_Type_L1B:EV_1KM_RefSB
gdal_translate -of GTiff -b 1 HDF4_EOS:EOS_SWATH:"d:\modis\1b\MOD021KM.A2011008.0850.005.2011008195744.hdf":MODIS_SWATH_Type_L1B:EV_1KM_RefSB d:\modis\1b\band_1.tiff
4) Warping the image to WGS84
gdalwarp -t_srs EPSG:4326 d:\modis\1b\band_1.tiff d:\modis\1b\band_1_warp.tiff
The example dataset, which i am using, can be downloaded here
ftp://ladsftp.nascom.nasa.gov/allData/5/MOD021KM/2011/008//MOD021KM.A2011008.0850.005.2011008195744.hdf
And now to my problem: I get always an certain shift (http://www.flickr.com/photos/54033867@N00/5363471425/in/photostream/), which is avoided if i am using the "Georeference MODIS" option in ENVI (http://www.flickr.com/photos/54033867@N00/5364083966/in/photostream/).
I also tried a few workarounds, f.g. http://thread.gmane.org/gmane.comp.gis.gdal.devel/10482, but nothing worked properly.
As far as I understand gdal supports Modis L1B SWATH, so what I am doing wrong? Any help is appreciated.
Regards Anna
P.S. I am using FWTools 2.4.7 on Windows
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