Survex Digest, Vol 4, Issue 3

[M.J. Green]

On Oct 7 2004, GRAHAM MULLAN wrote:

> I agree. Not only that, but many people calibrate their compasses in 
> such a way as to include both compass error and magnetic deviation in one 
> figure. Letting Survex deal with one part of this (I do not see any way 
> in which it can automatically deal with my compass!), will either lead to 
> confusion or to some folks not doing it correctly - or at all!

Of course confusion, caused by changing the way these errors are put in, is a problem.  Which I am sure will be taken into account, if anyone considers changing the implimentation.

However I think that it would be possible to specify the error in a particular instrument.  Using the *instrument command to specify the insturments that were used.  Then using a similar global method for applying the variation in magnetic north, the errors in the compass (which could again somehow be specifed by date) could be defined.  

I would not suggest that survex forces anyone to do the corrections in this way, in order to maintain backwards compatability.

I think approaching these long time scale corrections in a higher level way, would be a neat solution to making sure that all surveys had suitable corrections applied, particularly in large datasets.

Regards,
Martin