Impact of landmark parametrization on monocular EKF-SLAM with points and lines

Joan Solà (1) , Teresa Vidal-Calleja (1, 2) , Javier Civera (3) , Jose Maria Martinez-Monti (3)

1 LAAS - Laboratoire d'analyse et d'architecture des systèmes
2 ACFR - Australian Center for Field Robotics
3 DIIS - Departamento de Informática e Ingeniería de Sistemas

This paper explores the impact that landmark parametrization has in the performance of monocular, EKF-based, 6-DOF simultaneous localization and mapping (SLAM) in the context of undelayed landmark initialization. The work proposes a unified framework for points and lines that is independent of the parametrization used. Three parametrizations for points and five for straight lines are accurately described, emphasizing their similarities and differences. Monocular undelayed initialization challenges EKF because of the combination of non-linearity with large uncertainty associated to the non-measured DOF. In this regard, the goal of a good landmark parametrization is to improve the system's linearity as much as possible, improving the filter consistency, and thus achieving robuster and more accurate localization and mapping. The paper highlights and justifies the keys for satisfactory operation: inverse-distance parameters and landmark anchoring. It also defines a generalized linearity index suited for the EKF, and uses it to compute and compare the degrees of linearity of each parametrization. Finally, all parametrizations are benchmarked employing analytical and statistical tools, with simulations and real imagery data, using the standard and the robocentric EKF-SLAM formulations.

Mots clés: SLAM; initialization; vision; robotics

Domaines: Robotique [cs.RO]

Joan Solà, Teresa Vidal-Calleja, Javier Civera, Jose Maria Martinez-Monti. Impact of landmark parametrization on monocular EKF-SLAM with points and lines. 2010. ⟨hal-00451778v3⟩