It seems interesting I'll keep a note on this :)<br><br>The question is how you can build a VRT mosaic directly from MODIS hdf files, because<br>the problem is that you have to mosaic first and after that to transform them to the<br>
EPSG:4326 projection. If you transform them first and mosaic them after you might have<br>white lines.<br><br>--Nikos<br><br><div class="gmail_quote">2011/7/25 Brian Case <span dir="ltr"><<a href="mailto:rush@winkey.org">rush@winkey.org</a>></span><br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">anna, Nikolaos,<br>
<br>
after much experimentation I found something that seems to work.<br>
<br>
gdalwarp --config GEOL_AS_GCPS FULL \<br>
-tps -geoloc -t_srs EPSG:4326 \<br>
-te -119.88004906118 13.5092548294379 \<br>
-92.6036641645677 34.7070050511582 \<br>
HDF4_EOS:EOS_SWATH:"MOD02HKM.A2011169.1750.005.NRT.hdf":MODIS_SWATH_Type_L1B:EV_500_RefSB \ MOD02HKM.A2011169.1750.005.NRT.tif<br>
<br>
note i tried to escape the newlines to make it easy to read but the<br>
email may mess that up.<br>
<br>
there is about 2.7 million gcp's in a normal 5min modis swath file, by<br>
default gdal only reads every 10th row and column of gcp's this is not<br>
enough to handle the bowtie effect.<br>
<br>
<br>
Brian<br>
<br>
On Tue, 2011-01-18 at 16:33 -0800, Nikolaos Hatzopoulos wrote:<br>
> You are right, I notice that there isn't any difference from the<br>
> band_1.tiff and band_1_warp.tiff<br>
><br>
> --Nikos Hatzopoulos<br>
><br>
> On Mon, Jan 17, 2011 at 8:15 AM, anna auge <<a href="mailto:annaauge@web.de">annaauge@web.de</a>> wrote:<br>
> Hi all,<br>
><br>
> I am trying to convert modis level 1B data (type SWATH) to<br>
> geotiff following these steps.<br>
><br>
> 1) Examining the HDF<br>
> gdalinfo d:\modis\1b<br>
> \MOD021KM.A2011008.0850.005.2011008195744.hdf<br>
> gdalinfo HDF4_EOS:EOS_SWATH:"d:\modis\1b<br>
> \MOD021KM.A2011008.0850.005.2011008195744.hdf":MODIS_SWATH_Type_L1B:EV_1KM_RefSB<br>
> 2) Extracting the 1. band of the subdataset<br>
> MODIS_SWATH_Type_L1B:EV_1KM_RefSB<br>
> gdal_translate -of GTiff -b 1 HDF4_EOS:EOS_SWATH:"d:\modis\1b<br>
> \MOD021KM.A2011008.0850.005.2011008195744.hdf":MODIS_SWATH_Type_L1B:EV_1KM_RefSB d:\modis\1b\band_1.tiff<br>
> 4) Warping the image to WGS84<br>
> gdalwarp -t_srs EPSG:4326 d:\modis\1b\band_1.tiff d:\modis\1b<br>
> \band_1_warp.tiff<br>
><br>
> The example dataset, which i am using, can be downloaded here<br>
> <a href="ftp://ladsftp.nascom.nasa.gov/allData/5/MOD021KM/2011/008//MOD021KM.A2011008.0850.005.2011008195744.hdf" target="_blank">ftp://ladsftp.nascom.nasa.gov/allData/5/MOD021KM/2011/008//MOD021KM.A2011008.0850.005.2011008195744.hdf</a><br>
><br>
> And now to my problem: I get always an certain shift<br>
> (<a href="http://www.flickr.com/photos/54033867@N00/5363471425/in/photostream/" target="_blank">http://www.flickr.com/photos/54033867@N00/5363471425/in/photostream/</a>), which is avoided if i am using the "Georeference MODIS" option in ENVI (<a href="http://www.flickr.com/photos/54033867@N00/5364083966/in/photostream/" target="_blank">http://www.flickr.com/photos/54033867@N00/5364083966/in/photostream/</a>).<br>
> I also tried a few workarounds, f.g.<br>
> <a href="http://thread.gmane.org/gmane.comp.gis.gdal.devel/10482" target="_blank">http://thread.gmane.org/gmane.comp.gis.gdal.devel/10482</a>, but<br>
> nothing worked properly.<br>
> As far as I understand gdal supports Modis L1B SWATH, so what<br>
> I am doing wrong? Any help is appreciated.<br>
><br>
> Regards Anna<br>
><br>
> P.S. I am using FWTools 2.4.7 on Windows<br>
><br>
><br>
><br>
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><br>
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<br>
<br>
</blockquote></div><br>