Three-dimensional methodology for photogrammetric acquisition of the soft tissues of the face: a new clinical-instrumental protocol

Objectives: To define an acquisition protocol that is clear, precise, repeatable, simple and fast, and that is useful for analysis of the anthropometric characteristics of the soft tissue of the face. Materials and Methods: The analysis was carried out according to a new clinical-instrumental protocol that comprises four distinct phases: 1) set up of the portable equipment in the space in which the field analysis will be performed, 2) preparation of the subject, spatial positioning, 3) scanning of the subject with different facial expressions, 4) treatment and processing of the data. The protocol was tested on a sample comprised 66 female subjects (64 Caucasian, one Ethiopian, one Brazilian) who were the finalists in an Italian national beauty contest in 2010. To illustrate the potential of the method, we report here on the measurements and the full analysis that was carried out on the facial model of one of the subjects who was scanned. Results: This new protocol for the acquisition of faces is shown to be fast (phase 1 of about 1 h; phase 2, about 1.5 min; phase 3, about 1.5 min; phase 4, about 15 min), simple (phases 1-3 requiring a short operator training period; only phase 4 requires expert operators), repeatable (with direct palpation of the anatomical landmarks and marking of their positions on the face, the problem of identification of these same landmarks on the digital model is solved), reliable and precise (average precision of measurements, 0.5-0.6 mm over the entire surface of the face). Conclusions: This standardization allows the mapping of the subjects to be carried out following the same conditions in a reliable and fast process for all of the subjects scanned.