[gdal-dev] downsampling geotiff with a low-pass filter

[Kay F. Jahnke]

Hi all!

I have a very detailed GeoTIFF DEM of part of my target area (2m 
resolution). The remainder of the area is covered in 5m. So I'd like to 
downsample the moore detailed data to have everything in 5m for further 
processing. The nearest thing to what I have in mind is using -r 
average, but from signal processing theory I know that using a simple 
average over a block of data is not a good approximation for a low-pass 
filter. Also, since some of the source pixels are fully inside the 
target pixels and some are only partly (5 doesn't divide by 2), An 
average over all participating source pixels seems wrong. What would you 
advise?

With regards
Kay