[Gdal-dev] GDALWarpOptions - Destination dataset issue

[Guillaume Bourel]

Hi,

I am currently trying to warp GeoTiff data with any geographic 
coordinate system into WGS84 with Mercator projection, within a C++ project.

I do believe this should be done by using GDALWarpRegionToBuffer, which 
needs a GDALWarpOperation, which, itself, needs a GDALWarpOptions.


GDALWarpOptions reference explains :

    GDALDatasetH GDALWarpOptions::hDstDS
    <http://gdal.maptools.org/structGDALWarpOptions.html#o5>
    Destination image dataset - may be NULL if only using
    GDALWarpOperation::WarpRegionToBuffer()
    <http://gdal.maptools.org/classGDALWarpOperation.html#a7>.

but GDALWarpOperation::Initialize or GDALCreateWarpOperation both 
returns CE_Failure, if hDstDS is set to NULL
(behavior due to ValidateOptions() call, which checks hDstDS isn't 
NULL). Therefore, creation of the GDALWarpOperation fails.
And, as I don't have any destination file, my destination dataset is NULL.

I don't understand what I'm doing wrong,
if someone could explain me the way I should follow to successfully 
create a GDALWarpOperation in order to use it with GDALWarpRegionToBuffer.


Best regards,
Guillaume.

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