Three-dimensional facial capture using a custom-built photogrammetry setup: Design, performance, and cost

Abstract

Although stereophotogrammetry is increasingly popular for 3-dimensional face scanning, commercial solutions remain quite expensive, limiting its accessibility. We propose a more affordable, custom-built photogrammetry setup (Stereo-Face 3D, SF3D) and evaluate its variability within and between systems. Twenty-nine subjects and a mannequin head were imaged 3 times using SF3D and a commercially available system. An anthropometric mask was mapped viscoelastically onto the reconstructed meshes using MeshMonk (https://github.com/TheWebMonks/meshmonk). Within systems, shape variability was determined by calculating the root-mean-square error (RMSE) of the Procrustes distance between each of the subject's 3 scans and the subject's ground truth (calculated by averaging the mappings after a nonscaled generalized Procrustes superimposition). Intersystem variability was determined by similarly comparing the ground truth mappings of both systems. Two-factor Procrustes analysis of variance was used to partition the intersystem shape variability to understand the source of the discrepancies between the facial shapes acquired by both systems. The RMSEs of the within-system shape variability for 3dMDFace and SF3D were 0.52±0.07mm and 0.44±0.16mm, respectively. The corresponding values for the mannequin head were 0.42±0.02mm and 0.29±0.03mm, respectively. The between-systems RMSE was 1.6±0.34mm for the study group and 1.38mm for the mannequin head. A 2-factor analysis indicated that variability attributable to the system was expressed mainly at the upper eyelids, nasal tip and alae, and chin areas. The variability values of the custom-built setup presented here were competitive to a state-of-the-art commercial system at a more affordable level of investment.