Le dimanche 09 février 2014 à 15:55 +0100, Maciej Sieczka a écrit : > W dniu 09.02.2014 13:17, Vincent Bain pisze: > > > Perhaps a wiser solution would be to v.to.point (i) contour lines, > > (ii) breaklines, then merge them in a single raster an run > > r.surf.nnbathy. > > There is no need to v.to.points isolines before rasterizing them for > nnbathy. Unless you want to generalize the contour lines on purpose, > e.g. to minimize the staircase artifacts in the output raster map.
oops, sorry you are right : I forgot to say I first turn isolines to points (v.to.points, with the vertices option). > > As to breaklines, if these are linear features that indicate > surface discontinuity and have no elevation attribute, nnbathy has no > use of them (which you know already). If they are vector isolines, just > rasterize them straight away. If these are vector 3d lines, you'd need > to rasterize them interpolating their elevation at each cell of the > output raster map, which v.to.rast can't do. Here is my mistake. I have a 3d breaklines vector, and I expected v.to.rast being able to (i) get vertices z values and (ii) interpolate z between vertices... > At least it couldn't a few > years ago when I tried it. This could probably be approximated with > something like v.to.points -v -i dmax=<raster DEM resolution> + > v.to.rast, but that's suboptimal. > > > Finally I found on the web a custom solution based on a nice little > > python script named tin2raster, you can find it at the address > > bellow. I tried to contact Antonio, the guy who wrote it, but did not > > get a reply : > > > > http://digilander.libero.it/antonioall/python_tin2raster.html > > That tool utilizes Vect_tin_get_z > (http://grass.osgeo.org/programming6/tin_8c.html), which claims to be > able to perform such interpolation, not only along a linear 3d feature, > but on faces as well. Nice. > > I don't know, but I'd like v.to.rast to provide such feature too. understanding c libs content is definitely beyond my skills ! but in the end, having a v.to.rast module able to handle 3d polylines and faces would be really nice. Best, Vincent. _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
