Novice: Contours from GIF

Aldo Clerici alcl01 at
Thu Sep 18 13:33:10 EDT 1997

At 08.06 18/09/97 +0000, you wrote:
>I've scanned most carefully a portion of a topographic map, ensuring
>that each pixel matches my resolution of five metres.  So my GIF file is
>600 x 800 pixels, 3km by 4km.
>I've been able to import it using and then adjust it's location
>using  Displaying it actually worked too, with d.rast.
>1)  how do I make the display show only one portion of the area and
>magnify it to show the original level of detail? Or better?
>2)  how do I now digitise the GIF to produce a vector map of the
I usually use: 
   r.thin (to thins lines)
   r.line (to create a binary vector file) (to build the dig_plus file)
   v.digit (to label contour lines).
   If you have only contours on your GIF map, that's all you have to do, but
if you have other         features you have to reclass (whit v.reclass) the
vector map saving only the labbelled contours
   in a new file.
   Hoping this helps you.
   Aldo Clerici
   Dip. Scienze della Terra
   Universita' di Parma

   And a site map of some of the features?
>James Cameron                                    (cameron at
>Digital Equipment Corporation (Australia) Pty. Ltd. A.C.N. 000 446 800

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