How to develop a dem map

[Michel Wurtz - ENGEES/CEREG]

Antonio Rodríguez Verdugo wrote:
> 
> Hi all,
> 
> I'm trying to develop a dem map, but instead of altitudes, I want to
> display animal and plant population densities. I've tried with v.digit to
> create a contour map, then v.to.rast, and then r.surf.contour. But I do not
> get a good result. I think my problem is in the v.digit module, I don't
> know exactly how to define the lines or areas regarding  densities.

It depends on what you have as initial data : if you have some
"isolines" for the density, you can digitize them, giving each
line a density as attribute, then v.to.rast and r.surf.contour.
Your line contour map should be seen exactly as a altitude contour
map.  So it is important that each line is labelled with the
number it represents.

If you have mesured the density at some places, you will find
easier to enter your mesures in a site file (x, y, value), then
run s.to.vect then v.to rast, and finaly s.surf.tps. You will
interpolate between points instead of lines.

-- 
Michel Wurtz    ENGEES - CEREG
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