2011/6/1 Chaitanya kumar CH <[email protected]> > Giovanni, > > You can use the -et option of gdalwarp. [1]
> Are you sure qgis is warping the whole image and not just the scaled down > version of the original? Processing a half giga pixel image ought to be > longer than instantaneous. > Probably you're right... I will investigate more. Thanks for the hint. > > [1]: http://www.gdal.org/gdalwarp.html > > On Wed, Jun 1, 2011 at 9:55 PM, G. Allegri <[email protected]> wrote: > >> I was doing some tests on Gvsig for raster reprojection, where gdal warp >> is used. Gvsig uses a default error threshold of 0.125, which AFAIK makes >> gdal warp fall back to an approximate transformation. Anyway the >> reprojection is quite slow, even if significantly faster then >> GDALGenImgProjTransform. >> >> My test is against a 21698P x 24647L ArcInfo Binary Grid, with a single >> band with block dimensions 256x4. Bot SRSs are projected. >> The command is: > gdalwarp -s_srs EPSG:3003 -t_srs EPSG:23032 -et 0.125 >> hdr.adf test.tiff >> It took about 9 minutes to complete. >> >> Loading the same raster on QGis, which implements its own approximate >> transformation for on-the-fly reprojection [1], is istantaneous. >> I was wondering if a similar algorithm could be use within Gdal... >> >> Giovanni >> >> [1] >> http://trac.osgeo.org/qgis/browser/trunk/qgis/src/core/qgsrasterprojector.cpp >> >> >> >> _______________________________________________ >> gdal-dev mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/gdal-dev >> > > > > -- > Best regards, > Chaitanya kumar CH. > /tʃaɪθənjə/ /kʊmɑr/ > +91-9494447584 > 17.2416N 80.1426E >
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