[gdal-dev] gdalwarp cutting off projected image

[Frank Warmerdam]

Scott Lewis wrote:
> Hi,
> 
> I'm fairly new with GDAL, and have been working with a coworker who is a 
> little more familiar with GDAL and gdalwarp, but we are both stumped by 
> this particular issue.
> 
> I have a GeoTiff image that is in a north polar Lamber Azimuthal Equal 
> Area (laea) projection.  I am trying to reproject it using gdalwarp to a 
> cylindrical projection (like EPSG:4326).  I am using the following command:
> 
> gdalwarp -t_srs EPSG:4326 input.gtiff.tif output.gtiff.tif
> 
> The tool runs OK, but when I open output.gtiff.tif, the projection is 
> "incomplete".  The parts that are there look correct, but it seems 
> everything above about 50 degrees is cut off, like the input.gtiff.tif 
> had a big circle around 50 degrees cut out before the reprojection was 
> made.
> 
> I've tried looking at the options for gdalwarp, but can't seem to find 
> anything that would help.

Scott,

There are various challenges in pole (or even dateline) spanning
reprojection operations.  The options at:

http://www.gdal.org/structGDALWarpOptions.html#0ed77f9917bb96c7a9aabd73d4d06e08

may be helpful.

In particular, you might try specifying -wo SOURCE_EXTRA=1000 or some similar
large value on the gdalwarp commandline.  It is also possible that the
SAMPLE_GRID=YES and SAMPLE_STEPS=100 options might help but generally if
you have lots of RAM and a not-too-big input image specifying a large
SOURCE_EXTRA value will resolve the issues.

Best regards,
-- 
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