[GRASSLIST:9110] Re: Raster-2-Vector Methodology Sugestions?

[Hamish]

> >>I have a scanned color topo map an would like to filter out the
> >brown >topo lines from blue rivers/grid lines and black writing, then
> >>vectorize them to have just a contour map.
> >>
> >>So far I have not been very happy with the results. And I was
> >>wondering if anyone has had any good experience and could share
> >their >steps to get good results.
> >>
> >>I first ran i.cluster & i.maxlik, r.mapcalc to get the group that
> >was >mainly the contours, r.thin , and then converted them to vector.
> >
> >what about loading into the GIMP or similar, select -> by color,
> >select -> invert, edit-> cut, save. Then r.in.gdal, r.null, r.thin,
> >r.contour or r.to.vect.
..
> have you got a sample of this operation? I'd like to put a walktrough
> about this operation on my site...

No, I don't have a sample. Great if you could put together a
walk-through though. Many GRASS tasks are not hard; just require knowing
how...


Hamish