[GRASS-user] Coordinates from distances

[Hamish]

Daniel wrote:
> Might be a bit off topic but here we go:
> I need to calculate coordinates for several
> points, something similar to m.cogo, but instead
> of having distance + bearing information, I'll
> have distance from at least 3 fixed, known
> landmarks. Is there a tool already built for
> this?

not that I know of, but see also v.in.geodesic and
v.transect(s) in addons and the r.transect module.

> If not, I tough about using a combination of
> v.buffer + v.overlay in order to cross circles
> representing the possible location of each point
> from the landmarks.

yup, my first try would be v.buffer + v.patch +
'v.clean tool=break error=intersection_points', but
the Venn overlap area made by v.overlap may be
better if the ranges are sloppy.

http://grass.osgeo.org/grass60/screenshots/images/fire2.png


see also this previous investigation into using
distance from cell phone towers to find lost hikers:

http://grass.osgeo.org/wiki/Search_and_Rescue#Case_Studies


Hamish