Frank, Thanks for your reply.
Do you know if python can use the function GDALSuggestedWarpOutput2() ? I searched on web and found only the C/C++ examples. Regards, Agnes Frank Warmerdam wrote: > > agnes123 wrote: >> >> Dear all, >> >> i have one question on the default pixel size in gdalwarp. >> >> In gdalwarp, we can use -tr to determine output pixel size in x and y >> direction, however, if i omit the argument -tr , gdal will have a default >> pixel size value which is in target projection units. >> >> For example, if the orginal input raster which has geodetic projection >> with >> pixel size 0.000277778 (decimal degree), after projecting to Lambert >> Conformal Conic without typing the argument -tr, gdal will have output >> raster pixel size 28.793808m. What is the algorithm behind to obtain the >> value 28.793808? >> >> I was wondering if there is somebody who knows it. I would greatly >> appreciate it.Thanks! >> >> Regards, >> Agnes >> > > Agnes, > > The computation is done by the GDALSuggestedWarpOutput2() function. I > would > suggest you read it's documentation and if still in doubt scan through the > code. > > > http://trac.osgeo.org/gdal/browser/trunk/gdal/alg/gdaltransformer.cpp#L162 > > It is basically a heuristic to maintain approximately the same diagonal > size of a pixel in the destination coordinate system as it was in the > source coordinate system. > > Best regards, > -- > ---------------------------------------+-------------------------------------- > I set the clouds in motion - turn up | Frank Warmerdam, > [email protected] > light and sound - activate the windows | http://pobox.com/~warmerdam > and watch the world go round - Rush | Geospatial Programmer for Rent > > _______________________________________________ > gdal-dev mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/gdal-dev > > -- View this message in context: http://n2.nabble.com/default-pixel-size-in-gdalwarp-tp3341802p3376077.html Sent from the GDAL - Dev mailing list archive at Nabble.com. _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
