title: Validation of a vision-based, three-dimensional facial imaging system.
abstract: OBJECTIVE
  The aim of this study was to assess the accuracy of a newly developed three-dimensional (3D) imaging system in recording facial morphology.
  
  
  METHODS
  Twenty-one infants with cleft lip each had a full-face alginate impression taken at the time of primary lip repair, and a stone cast was constructed from each impression. Five anthropometric points were marked on each cast. Each cast was digitized, and the 3D co-ordinates of the five points were obtained using a co-ordinate measuring machine (CMM, Ferranti) of documented accuracy (9.53 microm). Each cast was scanned in four positions using a computerized stereophotogrammetry (C3D) system. The five points were located on the 3D images, and their 3D co-ordinates were extracted by three operators. The co-ordinate systems produced by C3D were aligned, via translation and rotation, to match the CMM co-ordinate system using partial ordinary procrustes analysis. The displacements of the adjusted C3D co-ordinates from the reference co-ordinates were then measured. Three different types of errors were identified: operator, system, and registration errors.
  
  
  RESULTS
  Operator error was within 0.2 mm of the true co-ordinates of the landmarks. C3D was accurate within 0.4 mm. The average displacement of points over the 21 casts at four positions for the three operators was 0.79 mm (median 0.68).
  
  
  CONCLUSIONS
  The presented 3D imaging system is reliable in recording facial deformity and could be utilized in recording cleft deformities and measuring the changes following surgery
authors.affiliation: Oral and Maxillofacial Surgery, Biotechnology and Craniofacial Research Section, Glasgow Dental Hospital and School, Glasgow, Scotland, UK. a.ayoub@dental.gla.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Ayoub
authors.forename: A
authors.initials: A
authors.lastname: Garrahy
authors.forename: C
authors.initials: C
authors.lastname: Hood
authors.forename: J
authors.initials: J
authors.lastname: White
authors.forename: M
authors.initials: M
authors.lastname: Bock
authors.forename: J P
authors.initials: JP
authors.lastname: Siebert
authors.forename: R
authors.initials: R
authors.lastname: Spencer
authors.forename: A
authors.initials: A
authors.lastname: Ray
mesh_terms: D002508:Cephalometry / Q000379:methods*; D002971:Cleft Lip / Q000473:pathology* / Q000601:surgery; D004867:Equipment Design; D005145:Face / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods; D007223:Infant; D008953:Models, Anatomic; D010780:Photogrammetry / Q000295:instrumentation / Q000379:methods*