A noncontact three-dimensional measuring system (liquid crystal range finder system) is described. Three-dimensional facial surface data (more than 30,000 points) could be obtained in 1 second, and the resolution was approximately 0.4 mm. The reliability and repeatability of the results were validated with a calibrating apparatus and a highly accurate contact-type three-dimensional digitizer. Consequently, the average of the measurement errors on a facial plaster model was 0.3 mm. Repeatability in measuring human faces was approximately 0.3 mm. Therefore, the total error in measuring human faces was approximately 0.5 mm. Because of the shortness of measuring time, this system was capable of scanning faces of infants without the need for sedation. The output of the liquid crystal range finder was demonstrated on an infant with cleft lip. The surface points improved by cheiloplasty, and the residual deformities were observed clearly. This system was thought to be the most suitable apparatus for measuring faces of infants (especially infants with cleft lip) and enabled us to analyze facial surface structure both qualitatively and quantitatively.
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