Survey with laser instruments

[Eric Madelaine]

We have used the same technique for building a network of fixed points 
in the Marguareis, some years ago.
This was done with similar laser theodolites, by cavers that are also 
professional surveyors. They stated that the resulting accuracy is 
centimetric, this confirm your statements.

Eric Madelaine


Andy Waddington wrote:
> Sometime before sending, Graham Mullan typed (and on Wednesday 2008-07-16 sent):
>
>   
>> I have no idea what sort of instrument you used for your surface 
>> survey in Austria but I don't quite understand what you mean by the 
>> "angular accuracy being very small". Can you re-phrase?
>>     
>
> Not our surface survey, but the Austrians'. They used laser theodolites to
> measure distance and relative angles to fixed points in the National mapping
> system, and thus produce a series of fixed reference points in our area.
> Since some of the leg lengths involved were of several kilometres, I am
> assuming that the angular resolution - both precision and accuracy - is
> very small, since these are supposed to be accurate fixes, and a tiny angular
> error over a multi-km leg will produce a significant error in space. (0.1 deg
> error over 6 km is still 10m on the ground, and I was given to understand that
> the error bounds on the fixes was more in the order of centimetres, which
> implies milli-degree accuracy).
>
> Obviously, since they were using theodolites to measure relative angles to
> two (or more) known points, we don't have to worry about all the usual sources
> of error for magnetic surveys (solar flares and so on). The one blunder that
> we spotted was something like a ten degree error in one of the measured
> angles ...
>
> Andy
>
>