[GRASS-user] Techniques using v.digit.

charles eriseres at airpost.net
Tue Jun 24 10:06:35 EDT 2008

Good day all,

I have used v.digit experimentally when digitizing contour lines from  
a topo map but have a questions about digitizing contour lines,  
building footprints, and other.  The module v.digit has tools for  
digitizing lines, boundaries and centroids.  Contour lines can be  
open or closed, forming a crude circle, square, etc.  When digitizing  
contour lines that are closed, would you use the line tool and close  
the contour lines using the snapping tool or would you digitize  
contour lines similar to this by using the boundary tool?  In  
general, is the boundary tool only used for polygons?  What about  
roads, and buildings?  Would you use the line tool, and after apply  
the snapping tool or would you digitize buildings and roads using the  
boundary tool?  Or does it matter?  Does the techniques matter when  
developing digital elevation models from topo maps?

I also have questions about edge matching using GRASS.  I am  
attempting to digitize and combine two adjacent maps but have not  
been successful.  One way I thought about doing this align the two  
adjacent maps and tape the two maps together, scan the taped  
sections, after georeference this portion, cut and possibly use  
v.patch to combine different map sections.  Is there an easier way  
this could be carried out?

Thanks for any techniques you have to offer.


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