Triangulation as a surveying technique

[Philip Underwood]

John Halleck wrote:
> On Wed, 22 Jan 2003, Sergey Sorokin wrote:
> 
> > [...]
>  
> > You must have at least three legs from each station to get all of them
> > fixed. If you have a station with 2 legs than it can be located in two
> > different places (unless it is directly on line between it neighbours),
> > so you will need some extra data to fix it at the single location.
> 
>   Three legs from each station is ambigious, there are two solutions,
>   mirror imaged across the plane defined by the three reference points.
>   Although adding another constriant (not in the earth for satilite
>   measurements, maybe away from the previous points for the cave)
>   it can work.
> 
Possibly marking whether the highest numbered point is on the left or
right when looking from the lowest numbered point ot hte middle one for
each triangle. That should make it unambiguous, and _moderately_ easy to
use, without being restrictive in where you place your stations.

The other thing to remember is that the accuracy of this method is best
when the triangles are approximately equilateral.

You also need to have a directional reading (compass, reference to sun
or stars) for at least one of the legs, if you wish to orient your
survey to north.