Hi Viktoras, I think you want to use the GDAL tools, http://gdal.org. You can download them as part of the precompiled binary FWTools at http://fwtools.maptools.org/
GDAL is a library which you can link into your own code. They also come with command line tools to let you manipulate raster and vector data. I just did a little test: Using a 1.83 GHz Intel Core Duo Mac Mini with 1 GB RAM gdal_translate grabbed a 700 x 700 window from a 63434 x 11679 tiff and wrote it out to a tiff in about 13 seconds. Grabbing the same window and writing to a jpg took a bit over 5 seconds. Example: to grab a 700x700 pixel window from near the middle and write it to jpeg: gdal_translate -srcwin 31000 5000 700 700 -of jpeg p2.tif out.jpg To shrink it to 5% of original size (took about 13 seconds) gdal_translate -outsize 5% 5% -of jpeg p2.tif out.jpg Cheers, Rich On Feb 18, 2008 6:36 AM, viktoras <[EMAIL PROTECTED]> wrote: > hi friends ;-), > > just wanted to ask for any practical hints (algorithms) on downsampling > very large raw binary (32 bit integer) raster file from disk. Looking > for an algorithm or library that could be implemented or used in Ada, > C/C++, Fortran, Assembly, Perl, Python or whatever else. The simpler the > better :-). My aim is to subsample 2-4 gigabyte raster data file without > loading it into RAM within 10 seconds on an "ordinary" PC with Intel > processor (Windows, Linux, MacOSX on Intel). Wishing to explore as many > options as possible... If you know any paper or website dealing with > this kind of algorithms, I would appreciate the url. > > For example I have 50000x50000 raster and I need a portion of it resized > to 700x700... > > Thanks in advance > All the best! > Viktoras > _______________________________________________ > Geowanking mailing list > [email protected] > http://lists.burri.to/mailman/listinfo/geowanking > -- Rich Gibson Chief Scientist (and bottle washer), Locative Technologies http://mappinghacks.com http://geocoder.us http://testingrange.com AIM period3equals
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