LRUD (was Re: Survex digest, Vol 1 #136 - 3 msgs)

[David Doolin]

On Thu, 2 Aug 2001, Olly Betts wrote:

> On Wed, Aug 01, 2001 at 11:29:58AM -0400, Richard Knapp wrote:
> > LRUD are dependant on a shot but there are three ways they can be taken:
> > 
> > 	- perpendicular to next;
> > 	- perpendicular to last;
> > 	- average between last and next.
> 
> There's more than that - for instance, some people take them "across the
> passage".  Roughly speaking this means that the L/R line is perpendicular to

[]

> But in the interests of having something to implement, if you're going to
> pick one allowed style then LRUD readings at stations along the leg bisector
> is the one to go for.  Others can be added later once the simplest case is
> working.


One more comment, then I promise to shut up.

For the internal implementation, it would probably be easiest 
to implement the simplest,  *mathematically unique* representation.  
For the previous example of geological orientation data,
internally everything is dip/dip direction since this 
uniquely defines a plane in 2 coordinates by its pole.
(Which means I can compute orientation tensors etc .
immediately.)  But no one else needs to know this... they 
just enter their favorite format and it just works.

(At one point I had this running as an applet [ca. 1996].
But I haven't actually seen the code in years...)

-dmd


> 
> Cheers,
> Olly
> 
> 
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