Contour vectorization

[DIETER LEHMANN]

Hi David,
try mapscan:

http://www.undp.org/popin/softproj/download/mapscan/win/setup.ht
m

it is for Windows, but free...

Mapcsan handle only black and white images, you have to 
seperate the colors (for example with grass), and create a bw-
image.

Dieter

Date sent:      	Thu, 16 Mar 2000 15:19:18 +0000
From:           	David Osborne <David.Osborne at nottingham.ac.uk>
To:             	grasslist at baylor.edu
Subject:        	Contour vectorization

> I would like to be able to take a colour scanned image of a map and 
> extract the contours as vectors, to be able to prepare a DEM of the 
> scanned area. From what I've read of the online GRASS manual pages, it 
> seems that r.thin and r.line might help me get started... am I on the 
> right track? Has anyone tried this already who could give a methodology 
> for achieving what I want? The end result should be a DEM raster I can 
> use with ERDAS Imagine.
> 
> Is there any other software outside of GRASS I should be considering? 
> I've heard of GSNAKE but I'm not sure that does what I want. I'm really 
> looking for interactive line-following software, where the operator 
> indicates a line segment by clicking on the endpoints and the software 
> follows the line between them, generating either a co-ordinate stream 
> or a vector as it goes.
> 
> Any help greatly appreciated...
> 
> David
> 
> -- 
> David Osborne                         david.osborne at nottingham.ac.uk
> School of Geography             phone/voicemail: +44 (0)115 951 3397
> University of Nottingham                    fax: +44 (0)115 951 3358
> Nottingham NG7 2RD, UK     http://www.geog.nottingham.ac.uk/~osborne
> 
>