Assessment of reproducibility and reliability of facial expressions using 3D handheld scanner

A Review on Automated Facial Nerve Function Assessment From Visual Face Capture

“…7. Multi-camera setup [55], RGB-D cameras [57], [58] and 3D hand-held scanner [60] used in 3D facial motion capture systems. [8]- [10], [55]- [59] are built upon the analysis of 3D facial landmark's trajectory during standardized facial movements.…”

“…The landmark trajectory only outlines the facial movement in a coarse manner, so it is unable to depict more in-depth morphological changes in facial soft tissue. To solve this problem, a few studies [60]- [64] introduced 3D surface-based measures. They first applied commercial 3D scanners such as 3dMDflex TM to repetitively capture the detailed 3D geometry of the face with repose and during facial expressions in a specified period of time.…”

“…Statistical analysis such as ANOVA and t-test showed high intra-observer and inter-observer reproducibility of such surface-based measures, which implied a potential more reliable and accurate method to assess facial nerve function. Recent studies [60] found that using mobile hand-held 3D scanners, e.g. Artec TM Eva (see Fig.…”

Accuracy of Mobile Device–Compatible 3D Scanners for Facial Digitization: Systematic Review and Meta-Analysis (Preprint)

“…Subconscious nose breathing, eye blinking, and lip twitching should also be carefully considered as these are the main sources of involuntary facial movements [16]. Ozsoy et al [17] reported that changes in facial expressions could affect the reproducibility and reliability of a scan, with the highest error values observed for a frightened facial expression and the lowest value observed for neutral facial expression. To reduce motion artifacts, the person should be instructed to maintain a neutral facial expression and avoid any head movement during image acquisition [55].…”

“…Compared with facial stone casts, wherein only direct anthropometric measurements of the faces can be performed for facial analyses, virtually reconstructed models of the face can be utilized for multidisciplinary purposes [11][12][13]. Facial landmarks can easily be extracted from a digital facial model, and the digitized data format enables image merging and advanced dimensional analyses, such as surface-to-surface distance measurements and volume misfit evaluations, using analytical computer software [3,[14][15][16][17]. In addition, digital facial scanning provides an efficient basis for dental education and facial recognition [18][19][20].…”