Gimbal Lock
What is gimbal lock and how to avoid it?
GLOSSARY
Gimbal Lock occurs in 3D animation when two of the three rotation axes of an object become aligned in parallel, resulting in the loss of one degree of rotational freedom. This can lead to unexpected and often undesirable results in animations, where a character or object suddenly snaps to a new orientation.
In a 3D modeling program, rotating an aircraft's nose up 90 degrees aligns the yaw and roll axes, causing gimbal lock. If the animator then attempts to roll the aircraft, it yaws instead, disrupting the intended animation sequence.
Technical definition
To avoid gimbal lock, animators often use quaternion rotation systems or add an extra rotation order, which don't suffer from this limitation and provide smoother and more reliable control over object rotations.