title: Automated landmark extraction for orthodontic measurement of faces using the 3-camera photogrammetry methodology.
abstract: OBJECTIVE
  To set up a three-dimensional photogrammetric scanning system for precise landmark measurements, without any physical contact, using a low-cost and noninvasive digital photogrammetric solution, for supporting several necessity in clinical orthodontics and/or surgery diagnosis.
  
  
  METHODS
  Thirty coded targets were directly applied onto the subject's face on the soft tissue landmarks, and then, 3 simultaneous photos were acquired using photogrammetry, at room light conditions. For comparison, a dummy head was digitized both with a photogrammetric technique and with the laser scanner Minolta Vivid 910i (Konica Minolta, Tokyo, Japan).
  
  
  RESULTS
  The precise measurement of the landmarks is ranged between 0.017 and 0.029 mm. The system automatically measures spatial position of face landmarks, from which distances and angles can be obtained. The facial measurements were compared with those done using laser scanning and manual caliper. The adopted method gives higher precision than the others (0.022-mm mean value on points and 0.038-mm mean value on linear distances on a dummy head), is simple, and can be used easily as a standard routine.
  
  
  CONCLUSIONS
  The study demonstrated the validity of photogrammetry for accurate digitization of human face landmarks. This research points out the potential of this low-cost photogrammetry approach for medical digitization.
authors.affiliation: Orthodontic Specialization, Università Cattolica del Sacro Cuore di Roma, Rome, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Deli
authors.forename: Eliana
authors.initials: E
authors.lastname: Di Gioia
authors.forename: Luigi Maria
authors.initials: LM
authors.lastname: Galantucci
authors.forename: Gianluca
authors.initials: G
authors.lastname: Percoco
mesh_terms: D000886:Anthropometry / Q000295:instrumentation / Q000379:methods*; D001331:Automation; D005145:Face / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods*; D010780:Photogrammetry / Q000295:instrumentation / Q000379:methods*