[GRASS-user] How to find out an angle between to points on the map (for r.plane, r.lake)

[Hamish]

Dylan Beaudette wrote:
> > Well of course I had to go and try this out.
> >
> > attached is a patch (against todays SVN) to optionally print the
> > bearing between clicks.


Hi,

you should add a check so that it won't allow bogus results if the
location is in Lat/Lon:

e.g. from d.grid:
if (geogrid->answer && G_projection() == PROJECTION_LL)
  G_fatal_error(_(".. option is not available for LL projection"));

(the great circle line's bearing changes with distance along it; unless
you are interested in the rhumbline?)


for this stuff also checkout m.cogo, r.transect, r.profile,
d.rhumbline, d.geodesic


Hamish



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