Validation and reproducibility of a high-resolution three-dimensional facial imaging system

Abstract

Objective: To assess the accuracy and reproducibility of a high-resolution three-dimensional imaging system (Di3D). Design: The three-dimensional imaging system was validated in vitro using 12 adult facial plaster casts, which had landmarks marked, and the positions of the landmarks on the three-dimensional images captured by Di3D were compared with those obtained by a coordinate measuring machine (CMM). Methods: Operator error was measured by repeatedly locating landmarks on the three-dimensional image. Reproducibility error of the images was calculated by capturing three-dimensional images of the facial casts on two separate occasions; the Euclidean distance between the two matched sets of coordinates was then calculated. The Di3D system error was assessed by calculating the three-dimensional global positions of landmarks on the three-dimensional images and comparing them with those obtained by CMM (gold standard). Results: The operator error in placement of landmarks on the three-dimensional model was 0.07 mm, range 0.02-0.11 mm. The reproducibility of the Di3D capture was 0.13 mm, range 0.11-0.14 mm. The mean distance between the CMM and Di3D landmarks, which constitutes the Di3D system error, was an average of 0.21 mm, range 0.14-0.32 mm. Conclusions: The Di3D system error was within 0.2 mm, which is clinically acceptable, and offers considerable improvement in stereophotogrammetry for facial capture and analysis. © 2007 The British Association of Oral and Maxillofacial Surgeons.