[gdal-dev] help with resampling via python

[Chris Somerlot]

That was the other method I was trying, reading the VRT file into memory
using the new (to me) xml.etree.ElementTree lib. I was missing the
<AveragedSource> tag, though, thanks.

2009/4/1 Klokan Petr Přidal <klokan at klokan.cz>

> Hi Chris,
>
> You have two options in GDAL API for resampling via Python:
>
> gdal.RegenerateOverview() with 'average' and 'mode' algorithms.
> and
> gdal.ReprojectImage() with 'bilinear','cubic','cubicspline' and
> 'lanczos' algorithms.
>
> Example of such functionality is in gdal2tiles.py in function
> GDAL2Tiles.scale_query_to_tile():
>
> http://code.google.com/p/maptiler/source/browse/trunk/maptiler/gdal2tiles.py#1433
>
> I am resampling in memory (because I am working only with small tiles
> with usual size 256x256px):
>
> mem_drv = gdal.GetDriverByName( 'MEM' )
> target = mem_drv.Create('', outputXsize, outputYsize, bands)
>
> I think gdal.ReprojectImage() would be able to rescale also into VRT
> dataset.
>
> Another choice is to create copy into the VRT dataset and change the
> target raster size in XML attributes manually in the text.
> In that case the average algorithm in VRT is exposed by the
> <AveragedSource> tag...
>
> Best,
>
> Klokan
>
> 2009/4/1 Chris Somerlot <csomerlot at gmail.com>:
> > Having trouble figuring out how to resample an image to a different cell
> > size from python. I looked over the VRT driver page and have been trying
> to
> > get this to work:
> >
> > from osgeo import gdal
> >
> > gdal.AllRegister()
> >
> > src = gdal.Open('DOQ_test.TIF')
> > drv = gdal.GetDriverByName('VRT')
> > dst = drv.CreateCopy("", src, 0)
> >
> > dst.RasterXSize = '125'
> >
> > But it seems the cell size in the datasets and the bands are read only?
> Is
> > there any programmatic way to do this?
> >
> > _______________________________________________
> > gdal-dev mailing list
> > gdal-dev at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/gdal-dev
> >
>
> --
> http://blog.klokan.cz/
> http://www.maptiler.org/
> http://www.oldmapsonline.org/
>
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