[GRASS-user] resampling and patching DEM

[Glynn Clements]

Silvia Simoni wrote:

> I need to patch dems with different resolutions (1x1m) and (2x2 m) and  
> resample them to a coarser resolution (10x10 m). Which is the correct  
> procedure?
> 
> a. resampling the 1x1 dem to 2x2 using r.resampl.stats -w (to be more  
> accurate)
> patch them all at 2x2, resample the patched dem to 10x10m;
> 
> b.resample the 1x1 and 2x2 dem to 10x10 m separately using  
> r.resampl.stats -w, and then patch them all.

In most cases, the most accurate approach is to set the region to 1x1,
patch (which will resample everything to 1x1 by nearest-neighbour),
then resample to 10x10 with r.resamp.stats.

The problem with patching down-sampled data is that r.patch won't
merge partial results at the boundaries. It will simply discard choose
one value and discard the others.

-- 
Glynn Clements <glynn at gclements.plus.com>