[Gdal-dev] gdalwarp -rn(default) vs -rc

[Stephen Woodbridge]

Hi John, et al,

You example a) implies that you can supply multiple input files to 
mosaic into a single output file. Can you do that in one command? So 
multiple files names are on the command line and the last one is the 
output file? That would be very sweet.

Also do you know where the various options for -wo and -co are listed. 
They are not in the man pages. There is only the less than useful 
comment "There is a list of available ones. " and not reference as to where.

-Steve

John Mitchell wrote:
> Hi,
> 
> 
> Within gdalwarp where does using the higher quality option of -rc(cubic 
> resampling) verses the default of nearest neighbour resampling have the 
> greatest impact as far as quality and also as far as speed.
> Either
> a.) running gdalwarp to mosaic a number of tiles together and at the 
> same time reproject
> 
>   i.e.  gdalwarp.exe -wo SKIP_NOSOURCE=YES  -s_srs EPSG:" + EPSG + " 
> -t_srs EPSG:" + EPSG_wgs84 + " -rc -co tiled=yes -q " + inputFiles + " " 
> + rasterFile
> 
> b.) running gdalwarp to reduce the resolution but not changing the 
> projection and not mosaicking
>  i.e.  gdalwarp.exe -tr " + psx + " " + psy + "  -s_srs EPSG:" + 
> EPSG_wgs84 + " -t_srs EPSG:" + EPSG_wgs84 + " -rc -co tiled=yes -q " + 
> rasterFile + " " + warpedSplitRasterFile
> 
> 
> Will it be faster to reduce resolution against a file via gdalwarp that 
> has already been reduced and will the quality be the same?  As an example:
> 1.) I mosaic a number of tiles at full resolution
> 2.) I reduce the mosaic from 1 by 1/2
> 3a.) I reduce the mosaic from 1 by 1/4
> 3b.) I reduce the mosaic from 2 by 1/2
> 
> Between 3a and 3b will 3b be faster and will the quality be the same?
> 
> Any other suggestions on speeding up gdalwarp would be appreciated.
> 
> Thanks,
> 
> 
> -- 
> John J. Mitchell
> 
> 
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