Markus, If I understand your problem correctly you should be able to use GDALDataset::BuildOverviews() and/or GDALRegenerateOverviews() for this task. To avoid a temporary file, you can use a GDAL virtual file<http://www.gdal.org/gdal_vrttut.html> . There is an example python code using these functions at http://trac.osgeo.org/gdal/browser/trunk/autotest/gcore/tiff_ovr.py . You can find the documentation for the C++ version of these functions at http://www.gdal.org/classGDALDataset.html#2aa6f88b3bbc840a5696236af11dde15and http://www.gdal.org/gdal_8h.html#f42fd5ddd2d160492b23d62e75e42c82 . You may need to use the trunk version of GDAL (refer to http://trac.osgeo.org/gdal/wiki/DownloadSource#Subversion) for these functions. I hope this can solve your problem.
Best regards, -- Chaitanya kumar CH. On Tue, Jun 23, 2009 at 4:29 PM, Markus Reinhold <[email protected]> wrote: > Hej everyone, > currently I was able to finish a small Python project utilizing GDAL for > creating quicklooks of satellite imagery. What I am doing right now is > retrieving the statistics of input bands, applying a standard deviation > stretch and saving the result as PNG-dataset. This works quite well, > however my problems start right here. To actually resize the created > dataset and to merge three separate bands into a single PNG-file I'm > using the Python Imaging Library, which needs single files to read from > in order to do any processing. There is no problem with small to > medium-sized images. But I'm running into trouble trying to create a > quicklook for some standard panchromatic Quickbird imagery (ca. 30000 x > 30000 pixels, 0.6 m GSD at UInt16 -> about 1.9 GB file size) as the PNG > file that is created temporarily gets very big. The neccessary I/O > operations naturally take quite some time. So my question is the > following: Is there any possibility to do resizing a dataset with GDAL > means - to spare the creation of a temporary file? > Thank you very much for any ideas. > Regards, > Markus Reinhold > > -- > > ******************************************************** > Dipl.-Kartograph Markus Reinhold > > Chair of Geoinformatics, Geohydrology and Modeling > Friedrich-Schiller-University Jena > Löbdergraben 32 > D - 07743 Jena > Germany > > Phone.: (+49)(0)3641 / 9 488 65 > E-Mail: [email protected] > ******************************************************** > > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev >
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