Hi Hamish!
I can take out the z-values, so now I need to found the midline in the 2d
space.Can this be done in simplest way?
Thx for your support
Luca
ok, you are starting already with lines, not area boundaries, so no need
to turn boundaries into lines with v.type. (v.extract only works on
features with a category, thus v.category.) You can go to the v.to.rast
step directly, make a "one" map for the cost,r.mapcalc cost_map=1
then do r.cost -k, 'r.param.scale param=slope size=7', threshold at
about 30 degrees with r.mapcalc, r.thin.bonus: river width at any point is possible by using r.mapcalc to make
r.thin map have cost's values * 2, then r.grow out to the edges.BUT, looking at your data, the river is 30m wide so a 10m raster
resolution would make the output too coarse so this method is pretty
bad. Maybe ok if you used 1m resolution on a small section but
not practicable for the whole area.You need a vector solution for figuring out river width, someone else
will have to help you with that.
Hamish
--
"E' molto più bello sapere qualcosa di tutto, che tutto di una cosa (Blaise
Pascal)."
GENTOO-GIS Development Team
jabber: casagrande@jabber.linux.it