title: Precision and accuracy of the 3dMD photogrammetric system in craniomaxillofacial application.
abstract: BACKGROUND
  In modern anthropometry of such complex structures as the face, three-dimensional scanning techniques have become more and more common. Before establishing them as a criterion standard, however, meticulous evaluation of their precision and accuracy under both ideal and clinical circumstances is essential. Potential sources of error need to be identified and addressed.
  
  
  METHODS
  Under ideal circumstances, a phantom is used to examine the precision and accuracy of the 3dMD system. A clinical setting is simulated by varying different parameters such as angle, distance, and system reregistration, as well as data evaluation under different levels of magnification.
  
  
  RESULTS
  The handling of the system was unproblematic in matters of data acquisition and data analysis. It was very reliable, with a mean global error of 0.2 mm (range, 0.1-0.5 mm) for mannequin head measurements. Neither the position of the head nor that of the camera influenced these parameters. New referencing of the system did not influence precision and accuracy.
  
  
  CONCLUSIONS
  The precision and accuracy of the tested system are more than sufficient for clinical needs and greater than those of other methods, such as direct anthropometry and two-dimensional photography. The evaluated system can be recommended for evaluation and documentation of the facial surface and could offer new opportunities in reconstructive, orthognathic, and craniofacial surgery.
authors.affiliation: Clinic for Cranio-Maxillofacial Surgery, University Hospital of Zurich, Zurich, Switzerland. heinz-theo.luebbers@usz.ch
authors.forename: Heinz-Theo
authors.initials: HT
authors.lastname: Lübbers
authors.forename: Laurent
authors.initials: L
authors.lastname: Medinger
authors.forename: Astrid
authors.initials: A
authors.lastname: Kruse
authors.forename: Klaus Wilhelm
authors.initials: KW
authors.lastname: Grätz
authors.forename: Felix
authors.initials: F
authors.lastname: Matthews
mesh_terms: D000886:Anthropometry; D005145:Face / Q000033:anatomy & histology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D021621:Imaging, Three-Dimensional; D008348:Manikins; D019047:Phantoms, Imaging; D010780:Photogrammetry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012984:Software