“…Usually, traditional [ 17 , 18 , 19 , 20 , 21 ] and deep-learning-based face detectors [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ] are designed to process 2D images, but they have also been extended to analyze 3D data [ 30 , 31 , 32 , 33 ]. These approaches take advantage of deep information to be less sensitive to low/high illumination conditions and viewpoint variation in comparison to 2D face detectors.…”