On Tue, 17 Nov 2009 07:07:59 -0000, Raspaud Martin <martin.rasp...@smhi.se>
wrote:
>
> Now I would like to project satellite data for which I have the 2d lat
> and lon grids onto, say, a polar stereographic projection for example.
GDAL can do this using VRT files.
First create a VRT file to represent your raw data set, eg.
<VRTDataset rasterXSize="2048" rasterYSize="100">
<VRTRasterBand dataType="UInt16" band="1" subClass="VRTRawRasterBand">
<SourceFilename relativetoVRT="1">input.dat</SourceFilename>
<ByteOrder>LSB</ByteOrder>
<other stuff like ImageOffset, PixelOffset, LineOffset, ...>
</VRTRasterBand>
<other bands...>
</VRTDataset>
Then do similar for each of your latitude and longitude files, eg.
<VRTDataset rasterXSize="2048" rasterYSize="100">
<VRTRasterBand dataType="Float32" band="1" subClass="VRTRawRasterBand">
<SourceFilename relativetoVRT="1">latitude.dat</SourceFilename>
<ByteOrder>LSB</ByteOrder>
<other stuff like ImageOffset, PixelOffset, LineOffset, ...>
</VRTRasterBand>
<other bands...>
</VRTDataset>
and similarly for longitude.dat
Finally add pointers to the lat/lon VRT files into your data VRT
<Metadata domain="GEOLOCATION">
<MDI key="X_DATASET">longitude.vrt</MDI>
<MDI key="X_BAND">1</MDI>
<MDI key="Y_DATASET">latitude.vrt</MDI>
<MDI key="Y_BAND">1</MDI>
<MDI key="PIXEL_OFFSET">0</MDI>
<MDI key="LINE_OFFSET">0</MDI>
<MDI key="PIXEL_STEP">1</MDI>
<MDI key="LINE_STEP">1</MDI>
</Metadata>
Then use the data VRT as input to the gdalwarp program. You may need to
use the -tps option, see the manual page.
That's the general idea; let us know if you have any success or problems.
Andrew
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