[GRASS-user] [beginner][r.to.vect] -v? polygonizing only white parts of an image

[Hamish]

baobazz wrote:
> I'm trying to polygonize a raster.
> this raster is in black and white.
> 
> I want to polygonize only the white parts of the image.
> 
> I noticed that r.to.vect had a -v option allowing to polygonize certain
> parts of an image. Is it this option that I must use to vectorize the white
> parts of my image? If yes, how can I use it? If not, how to manage the
> operation?

use -v, but before that use r.mask, r.reclass, or r.mapcalc to make a MASK
map so only the white bits are visible to the r.to.vect module. After you
are done remember to remove or rename the MASK map :)


Hamish