title: Quantitative Evaluation of Stereo Visual Odometry for Autonomous Vessel Localisation in Inland Waterway Sensing Applications.
abstract: Autonomous survey vessels can increase the efficiency and availability of wide-area river environment surveying as a tool for environment protection and conservation. A key challenge is the accurate localisation of the vessel, where bank-side vegetation or urban settlement preclude the conventional use of line-of-sight global navigation satellite systems (GNSS). In this paper, we evaluate unaided visual odometry, via an on-board stereo camera rig attached to the survey vessel, as a novel, low-cost localisation strategy. Feature-based and appearance-based visual odometry algorithms are implemented on a six degrees of freedom platform operating under guided motion, but stochastic variation in yaw, pitch and roll. Evaluation is based on a 663 m-long trajectory (>15,000 image frames) and statistical error analysis against ground truth position from a target tracking tachymeter integrating electronic distance and angular measurements. The position error of the feature-based technique (mean of ±0.067 m) is three times smaller than that of the appearance-based algorithm. From multi-variable statistical regression, we are able to attribute this error to the depth of tracked features from the camera in the scene and variations in platform yaw. Our findings inform effective strategies to enhance stereo visual localisation for the specific application of river monitoring.
authors.affiliation: School of Energy, Environmental Technology and Agrifood, Cranfield University, Cranfield MK43 0AL, UK. t.kriechbaumer@cranfield.ac.uk.
authors.forename: Thomas
authors.initials: T
authors.lastname: Kriechbaumer
authors.affiliation: School of Aerospace, Transport Systems and Manufacturing, Cranfield University, Cranfield MK43 0AL, UK. k.blackburn@cranfield.ac.uk.
authors.forename: Kim
authors.initials: K
authors.lastname: Blackburn
authors.affiliation: School of Engineering and Computing Sciences, Durham University, Durham DH1 3LE, UK. toby.breckon@durham.ac.uk.
authors.forename: Toby P
authors.initials: TP
authors.lastname: Breckon
authors.affiliation: School of Engineering and Computing Sciences, Durham University, Durham DH1 3LE, UK. oliver.hamilton@durham.ac.uk.
authors.forename: Oliver
authors.initials: O
authors.lastname: Hamilton
authors.affiliation: School of Energy, Environmental Technology and Agrifood, Cranfield University, Cranfield MK43 0AL, UK. m.rivas-casado@cranfield.ac.uk.
authors.forename: Monica Rivas
authors.initials: MR
authors.lastname: Casado
keywords: GPS-denied environments; autonomous river navigation; autonomous watercraft; river monitoring; stereo vision; survey vessel; visual odometry