Rapid three-dimensional measuring system for facial surface structure.
ABSTRACT 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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Article: Analysis methods for facial motion[Show abstract] [Hide abstract]
ABSTRACT: Objective techniques to evaluate a facial movement are indispensable for the contemporary treatment of patients with motor disorders such as facial paralysis, cleft lip, postoperative head and neck cancer, and so on. Recently, computer-assisted, video-based techniques have been devised and reported as measuring systems in which facial movements can be evaluated quantitatively. Commercially available motion analysis systems, in which a stereo-measuring technique with multiple cameras and markers to facilitate search of matching among images through all cameras, also are utilized, and are used in many measuring systems such as video-based systems. The key is how the problems of facial movement can be extracted precisely, and how useful information for the diagnosis and decision-making process can be derived from analyses of facial movement. Therefore, it is important to discuss which facial animations should be examined, and whether fixation of the head and markers attached to the face can hamper natural facial movement.Japanese Dental Science Review 01/2009; 45(1):4-13.
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ABSTRACT: 3D digital surface photogrammetry is an objective means of documenting the quantitative evaluation of facial morphology. However, there are no standardized superimposition and measurement systems for surveying soft tissue changes. The aim of this study was to present a superimposition and measurement model for three-dimensional analysis of therapy-induced sagittal changes in facial soft tissue and to ascertain its applicability based on the reproducibility of 3D landmark positions. Twenty-nine children were examined (eight with cleft lip and palate, six with cleft palate, eight with Class III malocclusion and seven healthy controls, between 4.1 and 6.4 years). The mean time between examinations was 8.2 months for the patients and 8 months for the control group. Data was acquired with the DSP 400((c))imaging system. A mathematical model with seven superimposition points was developed. Two 3D images, one at the beginning and the other at the end of the examination, were generated. Both images were superimposed ten times. Ten landmarks for evaluating the soft tissue changes were geometrically defined on the superimposition image, put in place ten times, and measured. The landmarks' reproducibility was calculated via statistical intraoperator analysis. Measurement error was identified using the root mean square error (RMSE). The superimposition points were easy to locate and the landmarks well definable. All midface landmarks proved to be highly reproducible with an RMSE under 0.50 mm. The lower face landmarks demonstrated good reproducibility with an RMSE under 1 mm. The midface landmarks' precision fell below the range of accuracy, while the lower face landmarks' precision fell within the optoelectronic scanner device's range of accuracy (0.50-1 mm). As an accurate, non-invasive, millisecond-fast, non-ionizing and ad infinitum repeatable procedure, 3D digital surface photogrammetry is very well suited for clinical and scientific application in orthodontics. We developed a reliable superimposition and measurement model with 3D digital surface photogrammetry. This new capturing and measurement system provides a simple means of determining 3D changes in facial soft tissue. Our landmarks proved to be highly reproducible for the midface while revealing good reproducibility for the lower face.Fortschritte der Kieferorthopädie 05/2010; 71(3):221-34. · 0.89 Impact Factor
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ABSTRACT: Three-dimensional (3D) integration of a maxillary model into a facial model has only been possible by a complex procedure using face bow transfer after taking impressions of certain maxillary and facial parts. In this study, we aimed to develop a method for integrating a scanned maxillary model into a scan-realized facial model. A total of 19 patients with the medical indication for cone-beam computed tomography (CBCT) and orthodontic treatment were included in this study. Facial and maxillary scans were also taken. The construction of the integrated surface model required 10 steps. This integration procedure was evaluated by taking ten 3D dentofacial linear segment measurements in the integrated scan and the CBCT. These results were analyzed using descriptive statistics. All measurements demonstrated good intra-individual reliability. We observed almost perfect congruence between integrated scan and CBCT in vertical distances, while the sagittal measurements revealed more, yet clinically acceptable, deviations possibly caused by different error sources in either of the two methods. This new method is suitable for generating 3D integrated surface-scan models which can be used for growth and therapy control studies in orthodontics and other disciplines in the dentofacial fields. Since this method does not require ionizing radiation, it is highly recommendable as an application for children and adolescent patients.Fortschritte der Kieferorthopädie 03/2012; 73(2):126-37. · 0.89 Impact Factor