Three-Dimensional Facial Anthropometry Using a Laser Surface Scanner: Validation of the Technique

Abstract

Three-dimensional measurement and characterization of facial surface anatomy are fundamental to the objective analysis of facial deformity. However, existing clinical tools are inadequate. Recent innovations in laser scanning technology provide a potentially useful technique for accurate three-dimensional documentation of the face. The purpose of this study is to evaluate the reliability of interactive anthropometric landmark localization based on digitized three-dimensional facial images and to identify sources of error associated with the technique. Three-dimensional surface data were acquired using a commercially available laser scanning device (Cyberware 3030RGB digitizer), and all subsequent anthropometric analyses were performed interactively on the computer monitor. Four experimental conditions were studied, with 10 observations for each condition. A stable anthropomorphic model with prelabeled anatomic landmarks was scanned repeatedly under varying conditions of head inclination and position within the scanning gantry to determine the effect of these variables on the reliability of the technique. The scanning protocol was then repeated with the labels removed to evaluate the reliability of interactive localization of anthropometric landmarks on a digitized three-dimensional image. Optimal results were obtained with the head positioned in the center of the scanning gantry and with the Frankfort plane elevated 10 degrees from the horizontal. Under these circumstances, all 22 labeled landmarks were visualized and the variance in landmark localization was less than 0.6 mm in the x (horizontal), y (vertical), and z (depth) dimensions. Varying head position or inclination caused significant degradation of the digitized image. The variance of interactive landmark localization was analyzed in three dimensions. The reliability and the spatial orientation of variability were determined for each anthropometric point. These findings have direct implications for the clinical adaptation of this diagnostic tool for quantitative evaluation of facial surface anatomy.

Evaluation of Precision and Accuracy Assessment of Different 3-D Surface Imaging Systems for Biomedical Purposes

“…The ideal scanner should feature both: high accuracy and precision. Studies evaluating scanners in medicine have mostly investigated one special anatomical area with a particular scanner and found accuracy and precision of the 3-D devices reasonable enough to recommend them for clinical application without investigating if the specific scanning systems or maybe a different device is best suited for the anatomical region of interest [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Our study, testing various scanners based on different technologies on three different kinds of complex surfaces for the first time, is able to corroborate these findings.…”

“…With human subjects, reliable measurements exploring limitations in accuracy and precision of the systems would have hardly been possible, given a substantial amount of variables that cannot be standardized, such as skin translucency, reflectivity, colour or artifacts caused by movement [13][14][15][16][17][18]. So far, a number of publications used single scanners for anthropometric measurements or clinical studies of individual body regions [21][22][23][24][25][26]. When comparing scanner results with an established reference method (e.g.…”

The use of craniofacial superimposition for disaster victim identification

“…Surface scanning technologies such as laser scanners, photogrammetry cameras and other threedimensional systems (including three-dimensional digitizers and structured light systems) have advanced craniofacial landmark location [50][51][52] and facial anthropometry in both adults and juveniles [53][54][55][56][57][58]. These systems have benefited the field of orthodontic and plastic surgery with the ability to record subtle changes in surface morphology, especially important in the monitoring orthodontic treatment, facial growth and maxillofacial intervention [59,60].…”

Three‐dimensional surface acquisition systems for the study of facial morphology and their application to maxillofacial surgery

“…Bush and co-workers reported on the validity of measuring anthropometric landmarks using this device (22). They reported a number of potential errors that could occur:…”