Introduction and validation of an automatic and low-cost three-dimensional facial imaging system: a comparison to direct anthropometry and Vectra H1

Background: Three-dimensional (3D) imaging is a powerful tool for the analysis of soft tissue morphology. 3D photogrammetry outperforms conventional photogrammetric methods and gains popularity among plastic surgeons. However, commercial 3D imaging systems bundled with analytical software are costly. This study intends to introduce and validate an automatic, low-cost, and user-friendly 3D facial scanner. Methods: An automatic and low-cost 3D facial scanning system was developed. The system consisted of a 3D facial scanner running automatically on a sliding track and a 3D data processing tool. Fifteen human subjects underwent 3D facial imaging by the novel scanner. Eighteen anthropometric parameters were measured on the 3D virtual models and compared with caliper measurements (the gold standard). Further, the novel 3D scanner was compared to the commonly used commercial 3D facial scanner Vectra H1. Heat map analysis was used to evaluate the deviation between the 3D models obtained by the two imaging systems. Results: The 3D photogrammetric results were highly correlated with the direct measurement results (P<0.001). The mean absolute differences (MADs) were less than 2 mm. Bland-Altman analysis indicated that, for 17 of the 18 parameters, the largest differences within the 95% limits of agreement margin were within the 2.0 mm clinical acceptance. Heat map analysis showed the average distance between the 3D virtual models was 0.15 mm, with a root mean square of 0.71 mm. Conclusions: The novel 3D facial scanning system is proven to be highly reliable. It provides a good alternative to commercial 3D facial scanners.