[GRASSLIST:463] contour maps

I am trying to make some raster maps from contour maps that where
scanned to gif. The inicial maps are in RBG for and I split the channels
in to CYMB so that in the end I have a grey scale map where the contour
(that initial where in brown) are much more obvious, then I run a edge
detection algorithm and the result is fine.
The i pass the image to GRASS and run r.thin and v.poly the problem is
that the final result like a a group of cells all connected (it looks a
bit like thysson poligons). Since I had a bad experience with this
procedure I decided to digitalize the maps with the mouse, this is very
borring and time consumig
Does anyone has a suggestion, or why the r.thin>v.poly>v.digit that is
normally explained in the tutorials work so bad ???
I have send this same email some days ago I haven't seen it in the
mailing list, probably i send it to the wrong email address

--
Jorge Samuel Mendes de Jesus <jesus@bgumail.bgu.ac.il>