Efficiently Closing Loops in LiDAR-Based SLAM Using Point Cloud Density Maps

TL;DR

This paper introduces a LiDAR-based loop closure detection method using density maps and ORB features, enabling accurate and efficient SLAM across various sensors and environments.

Contribution

It presents a robust, sensor-agnostic pipeline for loop closure detection in outdoor SLAM using density-preserving projections and feature-based place recognition.

Findings

Accurately detects loop closures in diverse outdoor environments.

Works effectively across different LiDAR sensors and motion profiles.

Provides open-source code for the proposed SLAM pipeline.

Abstract

Consistent maps are key for most autonomous mobile robots, and they often use SLAM approaches to build such maps. Loop closures via place recognition help to maintain accurate pose estimates by mitigating global drift, and are thus key for realizing an effective SLAM system. This paper presents a robust loop closure detection pipeline for outdoor SLAM with LiDAR-equipped robots. Our method handles various LiDAR sensors with different scanning patterns, fields of view, and resolutions. It generates local maps from LiDAR scans and aligns them using a ground alignment module to handle both planar and non-planar motion of the LiDAR, ensuring applicability across platforms. The method uses density-preserving bird's-eye-view projections of these local maps and extracts ORB feature descriptors for place recognition. It stores the feature descriptors in a binary search tree for efficient retrieval, and self-similarity pruning addresses perceptual aliasing in repetitive environments. Extensive experiments on public and self-recorded datasets demonstrate accurate loop closure detection, long-term localization, and cross-platform multi-map alignment, agnostic to the LiDAR scanning patterns, fields of view, and motion profiles. We provide the code for our pipeline as open-source software at https://github.com/PRBonn/MapClosures.