Fig 1.
PRISMA flow diagram.
Table 1.
Overview of the participants, objective types, descriptions and findings.
Table 2.
Overview of participant interviews.
Fig 2.
Visualization of the data pipelines.
Different combinations of the methods in each section were adopted in different studies. Pre-processing and recognition methods used in commercial software were not included due to the lack of clarify on what algorithms were used in them. The face used in illustration was an average face generated from http://faceresearch.org/demos/average, which is available open access (CC-BY-4.0) [50]. The icons used in the figure are available open access (CC-BY) from the NounProject.com. 2D/3D: two/three-dimension, ANOVA: analysis of variance, AUROC: area under the receiver operating characteristic, CNN: convolutional neural network, IR: infrared, ISOMAP: isometric mapping, KNN: k nearest neighbor, LDA: linear discriminant analysis, ML: machine learning, RNN: recurrent neural network, ROI: region of interest, SVM: support vector machine.
Table 3.
Overview of data processing and statistical analyses.