# Experimental Comparison of Visual-Aided Odometry Methods for Rail Vehicles

## TL;DR

This paper evaluates visual and visual-inertial odometry methods for rail vehicles, demonstrating stereo visual-inertial odometry's potential for accurate, robust localization crucial for advanced railway operations.

## Contribution

It provides a comprehensive assessment of current visual-based odometry frameworks for rail applications, highlighting stereo visual-inertial odometry's advantages over other methods.

## Key findings

- Stereo visual-inertial odometry outperforms other methods in challenging environments.
- Visual-inertial odometry achieves high accuracy comparable to RTK-GPS.
- Challenges include environmental conditions affecting sensor performance.

## Abstract

Today, rail vehicle localization is based on infrastructure-side Balises (beacons) together with on-board odometry to determine whether a rail segment is occupied. Such a coarse locking leads to a sub-optimal usage of the rail networks. New railway standards propose the use of moving blocks centered around the rail vehicles to increase the capacity of the network. However, this approach requires accurate and robust position and velocity estimation of all vehicles. In this work, we investigate the applicability, challenges and limitations of current visual and visual-inertial motion estimation frameworks for rail applications. An evaluation against RTK-GPS ground truth is performed on multiple datasets recorded in industrial, sub-urban, and forest environments. Our results show that stereo visual-inertial odometry has a great potential to provide a precise motion estimation because of its complementing sensor modalities and shows superior performance in challenging situations compared to other frameworks.