Review of ORB-SLAM: a monocular SLAM system

ORB-SLAM

- Uses

- Bundle Adjustment
- ORB features [9]
- A pose graph
- Essential graph
- a spanning tree
- loop closure links
- strong edges
- from covisibility graph

- covisibliity graph
- local covisible area
- tracking and mapping

- mar point and keyframe selection
- generous spawning
- restrictive culling
- identify redundant keyframes
- improves robustness and lifelong operations

- Stores map points:

- 3D position X(w,i) in the world coordinate system
- the viewing direction n(i)
- the mean unit vector of all its viewing directions
- the ray that joint the point with the optical center of the keyframe

- A representative ORB descriptor D(i)
- the associated ORB descriptor whose hamming distance is minimum
with respect to all other associated descriptors in the keyframes
in which the point is observed.

- the maximum d(max)
- the minimum d(min) distance
- at which the point can be observed,
- according to the scale invariance limits of the ORB features.

- Stores keyframes k(i)

- The camera pose T (i,w)

- a rigid body transformation
- that transforms points from the world to the camera coordinate system

- the camera intrinsics
- including focal length and principal point

- all the ORB features extracted in the framee
- associated or not to a map point,
whose coordinates are undistorted if a distortion model is provided.

Comments

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