A comparison between stereophotogrammetry and smartphone structured light technology for three-dimensional face scanning

Objectives: To compare three-dimensional facial scans obtained by stereophotogrammetry with\r\ntwo different applications for smartphone supporting the TrueDepth system, a structured light\r\ntechnology.\r\nMaterials and Methods: Facial scans of 40 different subjects were acquired with three different\r\nsystems. The 3dMDtrio Stereophotogrammetry System (3dMD, Atlanta, Ga) was compared with a\r\nsmartphone (iPhone Xs; Apple, Cupertino, Calif) equipped with the Bellus3D Face Application\r\n(version 1.6.11; Bellus3D Inc, Campbell, Calif) or Capture (version 1.2.5; Standard Cyborg Inc, San\r\nFrancisco, Calif). Times of image acquisition and elaboration were recorded. The surface-tosurface deviation and the distance between 18 landmarks from 3dMD reference images to those\r\nacquired with Bellus3D or Capture were measured.\r\nResults: Capturing and processing times with the smartphone applications were considerably longer\r\nthan with the 3dMD system. The surface-to-surface deviation analysis between the Bellus3D and\r\n3dMD showed an overlap percentage of 80.01% 6 5.92% and 56.62% 6 7.65% within the ranges of\r\n1 mm and 0.5 mm discrepancy, respectively. Images from Capture showed an overlap percentage of\r\n81.40% 6 9.59% and 56.45% 6 11.62% within the ranges of 1 mm and 0.5 mm, respectively.\r\nConclusions: The face image acquisition with the 3dMD device is fast and accurate, but bulky and\r\nexpensive. The new smartphone applications combined with the TrueDepth sensors show\r\npromising results. They need more accuracy from the operator and more compliance from the\r\npatient because of the increased acquisition time. Their greatest advantages are related to cost and\r\nportability.