[Gdal-dev] Image Reprojection

[Frank Warmerdam]

Matt Lynch wrote:
> Hi,
> 
> I am interested in writing or using a windows command line utility which
> will reproject GeoTiffs for me.  It seems that the gdalwarp utility is
> what I want.
> 
> So I have a couple of questions ...
> 
> 1.  Am I correct that gdalwarp will reproject GeoTiffs for me?  (e.g.
> UTM to Decimal Degrees)
> 2.  Are there some usage examples that I can refer to?

Matt,

I trust you have read the modest docs at:

   http://www.remotesensing.org/gdal/gdal_utilities.html#gdalwarp

Yes, it can reproject GeoTIFF files from UTM to decimal degrees.   The only
example is the one in the documentation.  To do what you want you might use:

  gdalwarp -t_srs '+proj=latlong +datum=WGS84' in.tif out.tif

Note, there is also a "gdalwarptest" in the CVS version of GDAL with similar
commandline options as gdalwarp, but using a much more sophisticated approach
internally.  In particular, it:
  o Supports a all pixel types, not just 8bit like gdalwarp.
  o Will work on images that cannot be held completely in memory.
  o Supports a variety of resamplig kernels.
  o Has "NODATA" support.

Gdalwarptest is the "test harnass" for this next generation warper.  Depending
on your needs I would appreciate help in testing this new implementation.

Best regards,
-- 
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