Detailed facial ROI definition
The 22 unit local regions is defined as follows: (1 37 69 2); (37 42 41 40 70 69); (40 28 31 70); (28 43 71 31); (43 48 47 46 72 71); (46 17 16 72); (2 69 73 4 3); (69 70 74 73); (70 30 34 74); (30 71 75 34); (71 72 76 75); (72 16 15 14 76); (4 73 49 5); (73 74 62 49); (74 34 63 62); (34 75 64 66); (75 76 55 64); (76 14 13 55); (5 49 68 7 6); (68 67 58 9 8 7); (67 66 11 10 9 58); (66 55 13 12 11).
The 9 local regions for background LeTSrPPG feature are defined based on the landmark index in Figure 1 as follows: ROI.feature(1).ptsIdx = [0 1 2 3 72 73 33 30 29 28 27 39 40 41 36]+1;
ROI.feature(2).ptsIdx = [36 68 72 73 33 74 75 71 45 46 47 42 27 39 40 41]+1;
ROI.feature(3).ptsIdx = [27 28 29 30 33 74 75 13 14 15 16 45 46 47 42]+1;
ROI.feature(4).ptsIdx = [1 2 3 4 48 61 62 33 30 69 68]+1;
ROI.feature(5).ptsIdx = [68 72 48 61 62 63 54 75 71 70 30 69]+1;
ROI.feature(6).ptsIdx = [30 33 51 62 63 54 12 13 14 15 71 70]+1;
ROI.feature(7).ptsIdx = [3 4 5 6 7 8 66 62 33 73 72]+1;
ROI.feature(8).ptsIdx = [72 48 50 6 7 8 9 10 55 54 75 74 33 73]+1;
ROI.feature(9).ptsIdx = [33 62 57 8 9 10 11 12 13 75 74]+1;
We select 4 background regions close to landmark 1, 3, 15, 17 The side length of background regions is determined by the distance between landmark 20 and 25.