title: Markerless motion capture can provide reliable 3D gait kinematics in the sagittal and frontal plane.
abstract: Estimating 3D joint rotations in the lower extremities accurately and reliably remains unresolved in markerless motion capture, despite extensive studies in the past decades. The main problems have been ascribed to the limited accuracy of the 3D reconstructions. Accordingly, the purpose of the present study was to develop a new approach based on highly detailed 3D reconstructions in combination with a translational and rotational unconstrained articulated model. The highly detailed 3D reconstructions were synthesized from an eight camera setup using a stereo vision approach. The subject specific articulated model was generated with three rotational and three translational degrees of freedom for each limb segment and without any constraints to the range of motion. This approach was tested on 3D gait analysis and compared to a marker based method. The experiment included ten healthy subjects in whom hip, knee and ankle joint were analysed. Flexion/extension angles as well as hip abduction/adduction closely resembled those obtained from the marker based system. However, the internal/external rotations, knee abduction/adduction and ankle inversion/eversion were less reliable.
authors.affiliation: Department of Neuroscience and Pharmacology, University of Copenhagen, 2200 Copenhagen N, Denmark; The Danish Institute of Fire and Security Technology, 2650 Hvidovre, Denmark. Electronic address: msc@dbi-net.dk.
authors.forename: Martin
authors.initials: M
authors.lastname: Sandau
authors.affiliation: Department of Neuroscience and Pharmacology, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Koblauch
authors.affiliation: Department of Architecture, Design and Media Technology, Aalborg University, 9200 Aalborg Sv, Denmark.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Moeslund
authors.affiliation: Department of Informatics and Mathematical Modelling, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Aanæs
authors.affiliation: Department of Neuroscience and Pharmacology, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Tine
authors.initials: T
authors.lastname: Alkjær
authors.affiliation: Department of Neuroscience and Pharmacology, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Erik B
authors.initials: EB
authors.lastname: Simonsen
mesh_terms: D000843:Ankle Joint / Q000502:physiology; D001696:Biomechanical Phenomena; D005684:Gait / Q000502:physiology*; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D016059:Range of Motion, Articular; D012399:Rotation; D014741:Video Recording; D016138:Walking / Q000502:physiology
keywords: 3D reconstruction; Articulated model; Biomechanics; Dense point cloud; Gait analysis; Iterative closest point; Markerless; Motion capture; Photogrammetry; Stereo vision; Tracking