[GRASS-user] lines and raster surface

Markus Neteler neteler at osgeo.org
Sun Mar 14 06:14:29 EDT 2010

On Sat, Mar 13, 2010 at 9:07 PM, Malte Martin <malte at perlomat.de> wrote:
> I got some vector lines (with z- values) and I got a raster surface. I need
> to know if the lines are above, intersecting or under the surface. Is it
> possible to that in GRASS? And if so, how is the trick?

I hoped to suggest v.to.rast with the use=z parameter to you but it
only works for contour lines.

IMHO we need a 3D version of the G_plot_line2() function [1] to keep
also the Z value. This function is called in plot_line() in v.to.rast.

Maybe there is another possibility - but I think that this functionality in
v.to.rast would be useful.

After having obtained the raster map from the 3D vector line(s), the
rest is a simple r.mapcalc operation.


[1] http://download.osgeo.org/grass/grass6_progman/plot_8c.html#a8e856de4632aa9b8a679737ffb71631f

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