Description

Use the declination command to add lines of magnetic declination to the map. These are useful primarily in rogaining maps, where they facilitate compass bearings.

Declination Angle

The magnetic declination angle is obtained from the NOAA online calculator using the World Magnetic Model. An accuracy of ±0.5° is typical. In the event that the calculator is offline, you can provide a declination angle manually using the --angle option.

Appearance

Declination lines are spaced at one-kilometre intervals, or according to the --spacing option if passed. Small directional arrows are provided periodically along each line at 160mm intervals.

The --offset option shifts the lines along the horizontal, if fine-tuning is required.

Change colour using the --stroke option, with an RGB triplet (e.g. 800080) or web colour name (e.g. purple).