[gdal-dev] ReprojectImage and nodata

[David Shean]

Even, 
I encountered the issue you mention back in May:

http://osgeo-org.1560.x6.nabble.com/gdal-dev-ReprojectImage-and-nodata-td5057270.html

The current ReprojectImage nodata handling is a bit confusing.  Do you see a relatively simple fix to mirror the behavior of gdalwarp?  

Thanks.
-David

On Oct 23, 2013, at 10:25 AM, Even Rouault <even.rouault at mines-paris.org> wrote:

> Le mercredi 23 octobre 2013 19:05:18, Ochs, Elke ERDC-RDE-CRREL-NH a écrit :
>> ReprojectImage does not maintain areas of nodata as I would expect it
>> should.  Small areas of nodata are getting erased and larger areas are
>> reduced in size.  I'm reprojecting from geographic to Albers, using
>> approximately the same  cell size (converted from dd to meters).  I'm
>> using GDAL 1.9.2 in Python.
>> 
>> Gdalwarp does a better job of maintaining nodata cells.  Is there a way to
>> get ReprojectImage to handle nodata in a similar way?  
> 
> Elke,
> 
> Always difficult to diagnose those problems as there are a few variables to 
> consider.
> Looking at the code of GDALReprojectImage(), I see it should take into account 
> the source nodata value, but it will ignore the nodata value that you may have 
> set on the target dataset, contrary to gdalwarp. That might be your issue. 
> Your source nodata values are likely to become 0 in the target datasource.
> 
> Even
> 
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