[Gdal-dev] srtm warping question
Frank Warmerdam
warmerdam at pobox.com
Tue Apr 11 14:39:46 EDT 2006
Michael Heins wrote:
> listers;
>
> Continuation of my SRTM reprojection problem.
>
> I convert SRTM - BIL format into GeoTiff using Gdal_translate:
> (so GeoTiff is in lat/long geographic coords)
> gdal_translate -ot CInt16 -a_nodata -32768 c:\srtmtest\N43W071.bil c:\srtmtest\outll.tif
>
> Then I reproject lat/long GeoTif into a utm projection GeoTiff:
> gdalwarp -t_srs "+proj=utm +zone=11 +datum=WGS84" -ot CInt16 c:\srtmtest\outll.tif c:\srtmtest\oututm.tif
>
> The resulting outll.tif is representative of the BIL in a grayscale representation. This is as expected.
> HOWEVER, the resulting oututm.tif is all null; when viewed, it is all black.?? why?
> I have experimented with other sample tifs, and they seemed to be reprojected no problem. This leads me to believe the Bil->Tif conversion is producing an errored Tif in some manner?
>
> Can someone help me out with why this reprojection is not working? does it have something todo with forcing the output type to 16bits? And how can I go about to fix this?
Mike,
Why did you pick the data type CInt16 as opposed to Int16? CInt16 is
"complex int 16", and involves a real and imaginary component. I suspect
that the warper is not supporting complex data properly and that is why
you aren't getting a result.
Best regards,
--
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I set the clouds in motion - turn up | Frank Warmerdam, warmerdam at pobox.com
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