title: Vision-based markerless registration using stereo vision and an augmented reality surgical navigation system: a pilot study.
abstract: BACKGROUND
  This study evaluated the use of an augmented reality navigation system that provides a markerless registration system using stereo vision in oral and maxillofacial surgery.
  
  
  METHODS
  A feasibility study was performed on a subject, wherein a stereo camera was used for tracking and markerless registration. The computed tomography data obtained from the volunteer was used to create an integral videography image and a 3-dimensional rapid prototype model of the jaw. The overlay of the subject's anatomic site and its 3D-IV image were displayed in real space using a 3D-AR display. Extraction of characteristic points and teeth matching were done using parallax images from two stereo cameras for patient-image registration.
  
  
  RESULTS
  Accurate registration of the volunteer's anatomy with IV stereoscopic images via image matching was done using the fully automated markerless system, which recognized the incisal edges of the teeth and captured information pertaining to their position with an average target registration error of < 1 mm. These 3D-CT images were then displayed in real space with high accuracy using AR. Even when the viewing position was changed, the 3D images could be observed as if they were floating in real space without using special glasses.
  
  
  CONCLUSIONS
  Teeth were successfully used for registration via 3D image (contour) matching. This system, without using references or fiducial markers, displayed 3D-CT images in real space with high accuracy. The system provided real-time markerless registration and 3D image matching via stereo vision, which, combined with AR, could have significant clinical applications.
authors.affiliation: Department of Oral-Maxillofacial Surgery, Dentistry and Orthodontics, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo ku, Tokyo, 113 8656, Japan. suenaga-tky@umin.ac.jp.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Suenaga
authors.affiliation: Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan. h2.tran@yahoo.com.
authors.forename: Huy Hoang
authors.initials: HH
authors.lastname: Tran
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, Tokyo, Japan. liao@tsinghua.edu.cn.|Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China. liao@tsinghua.edu.cn.
authors.forename: Hongen
authors.initials: H
authors.lastname: Liao
authors.affiliation: Department of Mechano-Informatics, Graduate School of Information Science and Technology, The University of Tokyo, Tokyo, Japan. masamune.ken@twmu.ac.jp.|Faculty of Advanced Technology and Surgery, Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, Tokyo, Japan. masamune.ken@twmu.ac.jp.
authors.forename: Ken
authors.initials: K
authors.lastname: Masamune
authors.affiliation: Department of Mechanical Engineering, School of Engineering, Tokyo Denki University, Tokyo, Japan. take14-dohi82@mail.dendai.ac.jp.
authors.forename: Takeyoshi
authors.initials: T
authors.lastname: Dohi
authors.affiliation: Department of Oral-Maxillofacial Surgery, Dentistry and Orthodontics, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo ku, Tokyo, 113 8656, Japan. pochi-tky@umin.net.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Hoshi
authors.affiliation: Department of Oral-Maxillofacial Surgery, Dentistry and Orthodontics, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo ku, Tokyo, 113 8656, Japan. takato-ora@h.u-tokyo.ac.jp.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Takato
mesh_terms: D002138:Calibration; D005240:Feasibility Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D019647:Oral Surgical Procedures / Q000295:instrumentation*; D019047:Phantoms, Imaging; D010865:Pilot Projects; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed; D014584:User-Computer Interface; D014741:Video Recording