[GRASS-user] change the cell value of a geotiff

[Glynn Clements]

maven apache wrote:

> > r.mapcalc "NewMap=if(OldMap==999,null(),OldMap)"
> >
> 
> :(
> I have seen the docs,but I am not sure the usage of it.
> 
> My raster map is aa in the grass, and the to be changed value is 12.1,I want
> to change it to null,so can you build the commond for me ,:(

	r.mapcalc 'aa2 = if(abs(aa - 12.1) < 1e-6, null(), aa)'

Or, to modify the map in-place:

	r.null map=aa setnull=12.099999-12.100001

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