[GRASS-dev] how to apply a processing to a group?

Hamish hamish_nospam at yahoo.com
Tue Nov 14 23:31:15 EST 2006

Yann Chemin wrote:
> Say somebody imports a hyperspectral/hypertemporal image (i.e. AVIRIS
> / Modis8days comp for 2-3 years) and wants to process all the bands
> simultaneously.


> Simpler(?)
> ---------------
> Is there a way to apply a simple set of equations to the group itself,
> bands belonging to the group would then inherit the equations.

Not much outside the imagery modules will do that right now, AFAIK.
It would be nice if more raster modules could take advantage of i.group
groups. (maybe just a script that does bash loop below)

> More complicated (maybe?)
> --------------------------------------
> is there a way to select a root name (say modis_ref_2* and
> modis_ref_1*) and apply a beloved NDVI to the the pair matching
> extensions.

Use g.mlist + a shell loop:

for MAP in `g.mlist pat=modis_ref_2*` ; do
  echo "Processing [$MAP] ..."
  r.info -r $MAP

> is there a way to use group directly for display? (i.e. d.rast
> group_name=blabla mode=rgb combination=4,2,1).

d.rgb r= g= b=


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