IMU Preintegration

• Filtering : high complexity (hard to manage data)
• Fixed-lag smoothing : more accurate than filtering, still not efficient (in specific window, not full)
• full smoothing : highest accuracy, high complexity

preintegrated IMU factor : 수많은 imu 데이터를 효율적 사용 가능

Riemannian Geometry

Euclidean space : finite-dimensional inner product space over the real numbers

Manifold : locally resembles Euclidean space near each point (partial euclidean space)

Riemannian manifold : on the tangent space

Speical Orthogonal Group (SO(3)) : ground of 3D rotation matrix (tangent space to the manifold is denoted as so(3))

pose와 pose 사이에는 보통 relative pose로 줌

slowly varing bias model : i와 j 사이에서의 bias는 변하지 않음