“…We have introduced the optimal state constraint (OSC)-EKF [54,55] that first optimally extracts all the information contained in the visual measurements about the relative camera poses in a sliding window and then uses these inferred relative-pose measurements in the EKF update. The (right) invariant Kalman filter [56] was recently employed to improve filter consistency [25,57,58,59,60], as well as the (iterated) EKF that was also used for VINS in robocentric formulations [22,61,62,63]. On the other hand, in the EKF framework, different geometric features besides points have also been exploited to improve VINS performance, for example, line features used in [64,65,66,67,68] and plane features in [69,70,71,72].…”