Loop closure detection

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Source: cometlabs
See also: loop-closing-in-viorb

Loop closure

  • Process of observing the same scene by non-adjacent frames and adding a constraint (relationship? association?) between them
  • A long-term data association in the VSLAM Framework  (part of front end)
  • Sort of incorporates topological SLAM into metric SLAM

loop-closure

Importance

  • Final refinement step (in data association)
  • Important for obtaining a globally consistent SLAM solution, especially when optimising over a long period of time

Basic loop closure detection

Match the current frame to all previous frames using feature matching

  • Computationally expensive, not always suitable for real-time applications
  • For RT—a possible solution: Define key frames and perform the comparison with only the key frames

Problems with loop closure

  • False positive/perceptual aliasing: Places are different, but are perceived as the same
  • False negative: Places are the same, but perceived as being different
  • Abhilfe: precision recall curve