Comparative Analysis between Linear Measures from Bidimensional and Three-dimensional Images of the Face for Human Identification Purpose: A Pilot Study

Abstract

Introduction: Photo-anthropometry is a method of facial image comparison that consists of taking measurements on images. The objective of this study was to verify if facial measurements obtained from a two-dimensional (2D) image can be applied for the purpose of human identification when compared with measurements obtained from a three-dimensional (3D) image. Materials and Methods: In this cross-sectional research, a convenience sample was formed by 3D and 2D images of 12 participants. In these images, 35 linear measurements were taken between landmarks. The 2D images were obtained in different angles and norms (left and right sides, and front sides), and the measures were categorized into vertical, lateral, and lip regions. The data were organized in Excel®spreadsheets (Microsoft Corp., Redmond, Washington, USA) and submitted to descriptive statistics. Results: The vertical measurements in lateral norms were more divergent than the measurements of 3D images, whereas the measurements of the lip region showed less differences in all norms. In the lateral norms, vertical measures such as nasion-pogonion were underestimated by 14.35 mm, whereas this same measure was overestimated by 7.20 mm in the frontal norm. In the lip region, the most underestimated measures were crista philtri (left)-cheilion (left) at 5.95 mm and crista philtri (right)-cheilion (right) at 5.45 mm, and the most overestimated was cheilion (right)-cheilion (left) at 4.38 mm, all in the frontal norm. Conclusion: The facial measurements obtained in 2D images can be underestimated or overestimated depending on the angle and norm of each image.