> Question 1: Is it correct that in therion and in survex the declination is > specified exactly the opposite way?
Yes, it is like that. You are right, there should be explicit warning in the manual. > Therion handbook page 18: > true bearing = measured bearing + declination > > Survex 1.2.1 manual page 19: > (true bearing)=((bearing)-(declination zero err)) > > So in case that magnetic north is 2° east of geographic north, I have to > correct this in therion by -2 and in survex by +2. I am not sure with this. If you measure 0, true bearing would be 2 (assuming east is 90°), therefore I think you should use 2 in therion and -2 in survex. I assume, your situation is the same, as on this picture http://en.wikipedia.org/wiki/Magnetic_declination. > Question 2: > When I enter the measurement data in therion, the meridian convergence > is handled automatically (in case a "cs" is specified). However due to > historic > reasons most of our data is still in survex format. I import the ".3d" file > and > specify the "cs" during import. I assume that therion is not applying any > corrections > for the meridian convergence and I need to correct the bearings manually in > survex? It is probably like that. If you want to have precise coordinates in your .3d file according to your CS, all bearing should be corrected for meridian convergence. But I am not sure, if you should add or substract it from magnetic declination :) S.
