Fig. 2
From: Behavioural compass: animal behaviour recognition using magnetometers
Meerkat with collar, axes, and Earth’s fields. The orientation of the axes of the triaxial magnetometer fixed to a collar on the meerkat along with the directions of two of Earth’s naturally occurring fields: Earth’s magnetic field \( {\overrightarrow{B}}_E \) pointing towards the magnetic North Pole, and Earth’s gravity vector \( \overrightarrow{g} \) pointing vertically downwards