Mangled 3d file

[Olly Betts]

On Tue, Mar 03, 2015 at 08:43:46PM -0000, Graham Mullan wrote:
> View by Error will not work as there are no fixed loops. Without wishing to
> re-jig all your data myself, I suggest that where you have legs in which you
> have left out the back compass reading that, instead of just omitting (or
> rather using a dash) for the offending reading that, before the leg you
> insert a new data line:
> 
> *data normal from to tape compass clino ignoreall
> 
> To apply to that leg and then, after that leg insert, once more:
> 
> *data normal from to tape compass clino backcompass backclino ignoreall
> 
> I suspect - and this would prove - that your data is being compromised by
> these false readings and that this has knock on effects along the file
> 
> What surprises me is that Therion does not produce the same problem, as this
> program uses the Survex engine to crunch centreline data.

Therion will use cavern if it is installed - if it isn't, it has some
fallback code it uses instead.  IIRC, the test for whether cavern is
installed isn't very robust, and it isn't very obvious from the output
which code is actually getting used.  

Cheers,
    Olly