The calibrations were to grid north not true north
The little file help illustrate the problem. Either declination statement can be used (or both, as they don’t stack).
If the cs command is commented out, we get a level square, but a rotated square if the cs command is used.
So that was the solution, the difference between grid and true north.
 
I then used the north true command and this rotated it to be level, north grid then moved it back. So back to north true.
I am now unable to reproduce the the twisted again. I seem to be locked into this north command.
Even when the declinations are commented out, I cant get it to use the cs declinations. Whoops!
(yep I did restart the computer with no joy)
 
John
 
 
Sent: Wednesday, October 03, 2012 2:04 PM
Subject: Re: [Therion] Declination and the cs command
 
If declination is explicitly specified for centerline, automatic declination is turned off.
 
The reason, why you have a rotated map is probably "meridian convergence". I am not an expert in this topic, but coordinate system north is usually also rotated against true astronomical north.
 
Have you played with layout north settings? E.g. include:
 
north grid
 
in the layout? Are you able to measure somehow this artificial rotation? Therion in its output reports both - calculated magnetic declination and meridian convergence for cave area.
 
Another question? Do you measure declination against true (astronomical) or grid north?
 
S.
 
On 3 October 2012 13:54, John Stevens <john@k-stevens.co.uk> wrote:
It seems the cs command over writes any declination that has been set, using the date provided with the survey data.
 
I have a large batch of old data with some accurate local declinations given. Unfortunately these are overridden so I can’t compare my results with the original results.
How can I make sure my local declinations are used rather than the cs global declination.
 
Another problem on the same line. I have a set of data where the declination has been taken off the bearings, so the local declination is now 0 degrees but the cs command still adds a declination, moving it way out from its expected line.
 
Can we have therion having a priority for local declinations rather than the gobal cs delinations ?
 
John
 

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