Unobservable Directions in Vision-Aided and Lidar-Aided Inertial Navigation Systems

The unobservable directions of Vision-aided Inertial Navigation System (VINS) are uniform global translation and global rotations about the gravity vector, while the unobservable directions of Lidar-aided Inertial Navigation System (LINS) are the same as VINS, requiring only one feature to be observed.