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Preliminary evaluation of an electromagnetic three-dimensional digitizer in facial anthropometry
V F Ferrario1, C Sforza, C E Poggio
1Laboratorio di Anatomia Funzionale dell'Apparato Stomatognatico, Istituto di Anatomia Umana Normale, Facoltà di Medicina e Chirurgia, Università degli Studi di Milano, Italy. vferrario@cube.it
Objective:
In this investigation, the precision of a commercial three-dimensional digitizer in the detection of facial landmarks in human adults was assessed.
Methods:
Fifty landmarks were identified and marked on the faces of five men, on five women, and on a stone cast of the face of one man. For each subject, the three-dimensional coordinates of the landmarks were obtained twice using an electromagnetic three-dimensional digitizer, and the duplicate digitizations were superimposed using common orientations and centers of gravity. Metric differences between homologous landmarks were assessed, and Dahlberg's error was computed.
Results:
For both men and women, the error was 1.05% of the nasion-midtragion distance, while for the cast, it was 0.9%. When the duplicate digitizations were used to mathematically reconstruct the faces, and several distances, angles, volumes, and surfaces were computed, more than 80% of the measurements had coefficients of variation lower than 1%.
Conclusions:
The digitizer can assess the coordinates of facial landmarks with sufficient precision, and reliable measurements can be obtained.