Regarding the diff function "diff": computes the difference between 2 raster bands (b1 - b2) Since the result of diff could be a negative number, for example 99-150=-51, I suggest that there be an additional function that provides the absolute value of diff, which would be 51 in this example. Greg
On Jan 31, 2010, at 12:18 PM, Antonio Valentino wrote: > Hi Matt, > > Il giorno Mon, 25 Jan 2010 20:57:58 -0600 > Matt Klaric <m...@klaric.com> ha scritto: > >> On Mon, Jan 25, 2010 at 8:38 PM, Frank Warmerdam >> <warmer...@pobox.com>wrote: >> >>> I don't think the VRT approach supports actually adding >>> different images together, only overlaying and rescaling. >>> >>> >> However, pixel functions could be used in a VRT file to accomplish the >> desired outcome. >> >> --matt > > Indeed, it would require a pixel function for sum and the ScaleRatio > property of ComplexSource. > > I have just submitted a patch > > http://trac.osgeo.org/gdal/ticket/3367 > > that provides a set of standard pixel functions, including sum (of 2 > or more raster bands). > > Using this set of functions it should be quite easy to write a python > program that performs generic bands arithmetic. > > Best regards. > > -- > Antonio Valentino > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev