Networking in GRASS

[Evaristo QUIROGA]

        Hello GrassGurus:

We have been working for more than 3 years with GRASS. Until we have used it
as a graphic database with plotting aim and simple analysis of overlay
operations, proximity functions, spread functions and seek functions.
Lately we have developed some models with the combination of the map algebra
and unix scripts.

In this line of progressive complication we have gone into the network
problematic (transport of water through a system of irrigation channels,
ordering of a river network, etc) and its resolution in GRASS environment. 
That's my question: How is treated the problems that implicate networking in 
GRASS? Have they to be solved only by means of combination of r.mapcalc
instruccions in  UNIX scripts loops? Have they to accomplish any intermediate
step? Do the misterious, for me, cost maps and this asociate functions play
any role in this point? And, would the run times of the network functions 
allow real time applications?



As a first example of this problematic and other similars, here you are a
case:

We desire to improve the quality of our DEMs by means of incorporating 
complementary information to the contour lines, in the sites file to
interpolate. This new information is of points type (3d vertex points) and
linear type (stream networks, ridges, etc), which have been digitized from the
same maps as the contour lines. We want that this linear information 
to be reflected in the created DEMs. The trouble is that vectorial
information is 2D, it hasn't elevation. Here begin the problem:
        The stream and contour line vector maps are converted to raster.