Private practice, Sint-Michiels, Belgium.
Department of Electrical Engineering, ESAT/PSI, Katholieke Universiteit Leuven, Leuven, Belgium; Medical Imaging Research Center, Universitair Ziekenhuis Leuven, Leuven, Belgium.
Am J Orthod Dentofacial Orthop. 2020 Aug;158(2):286-299. doi: 10.1016/j.ajodo.2020.01.016.
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 ± 0.07 mm and 0.44 ± 0.16 mm, respectively. The corresponding values for the mannequin head were 0.42 ± 0.02 mm and 0.29 ± 0.03 mm, respectively. The between-systems RMSE was 1.6 ± 0.34 mm for the study group and 1.38 mm 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.
虽然体视摄影术在三维面部扫描中越来越受欢迎，但商业解决方案仍然相当昂贵，限制了其可及性。我们提出了一种更经济实惠的定制摄影设置（Stereo-Face 3D，SF3D），并评估了其在系统内和系统间的可变性。
使用 SF3D 和商业上可用的系统对 29 名受试者和一个人头模型进行了 3 次成像。使用 MeshMonk（https://github.com/TheWebMonks/meshmonk）将弹性体解剖学面具映射到重建的网格上。在系统内，通过计算每个受试者的 3 次扫描与受试者真实值（通过对非缩放广义 Procrustes 叠加后的映射进行平均计算得出）之间的 Procrustes 距离的均方根误差（RMSE）来确定形状变异性。通过类似地比较两个系统的真实值映射来确定系统间的变异性。使用两因素 Procrustes 方差分析来划分系统间形状变异性，以了解两个系统获取的面部形状之间差异的来源。
3dMDFace 和 SF3D 的系统内形状变异性的 RMSE 分别为 0.52±0.07mm 和 0.44±0.16mm。人头模型的相应值分别为 0.42±0.02mm 和 0.29±0.03mm。研究组的组间 RMSE 为 1.6±0.34mm，人头模型的 RMSE 为 1.38mm。两因素分析表明，系统引起的变异性主要表现在上眼睑、鼻尖、鼻翼和下巴区域。
这里提出的定制设置的变异性值在更具成本效益的投资水平上与最先进的商业系统具有竞争力。
