[Gdal-dev] GDALWarpOptions - Destination dataset issue

Guillaume Bourel gbourel at ago.fr
Thu Nov 23 10:45:03 EST 2006


Frank Warmerdam wrote :
> Guillaume Bourel wrote:
>> 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.
>
> Guillaume,
>
> It appears that support for null hDstDS has "rotted" through disuse.  I
> have made a few changes to the Validate() method that I hope will fix the
> problem, but I currently have no uses for this style of use of the warper
> so it is hard for me to check.  Can you grab the latest from CVS and
> see if this helps?
>
> Best regards,

Thanks a lot Frank,

I've made an update from CVS this morning and everything is now working 
well.

Guillaume.

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