DEVELOPMENT OF COMPUTER VISION BASED FACE TRACKING MEASUREMENT

DEVELOPMENT OF COMPUTER VISION BASED FACE TRACKING MEASUREMENT FOR SITTING ERGONOMICS Tommi Lintilä, Valtteri Hyvärinen, Reijo Kariniemi, Anjan KC, Lassi Nurmi, Taina Liukkonen, Seija Viinikka, Panu Kiviluoma, Aku Korhonen & Petri Kuosmanen

Content • Introduction • Sitting ergonomics • Why frontal webcam as a measurement device? • Principle of the measurement • Measurement algorithm with MATLAB • Experimental test setup • Results • Discussion

Introduction http: //www. lifehack. org/articles/lifestyle/15 -simple-but-powerful-back-exercises-ease-stiffness-and-lower-back-pain. html

Sitting ergonomics • Maximum of 30 minutes of sitting consecutively • Good posture • Ear, shoulder and hip should create a vertical line • ”Right” curvature in the spine • Poor sitting posture • Uneven loading to the spine • Pain and tissue degeneration http: //www. michelleowen. co. nz/ergonomics-and-the-body/

Why frontal webcam as a measurement device? • Almost everybody has one • Should be accurate enough http: //www. mytecharena. com/laptop-hardware/4/

Principle of the measurement • Head position tells something about the overall posture. • The approach is to use incremental measurement of the head position http: //www. wellwest. co. nz/img/sitting-posture. jpg

Measurement algorithm with MATLAB Coordinates of the head Good initial posture Slouching forward Side leaning Standing up Slouching down

Experimental test setup • 15 minutes test sessions • A physiotherapist looked the videos afterwards, and tried to find out the same events as the software did

Results • Bad initial posture! Expert 36 Both 9 Software 33 • Detected changes in posture • System could detect 25 % of the events that the expert observer detected.

Results • In three out of ten tests the software detected face only 4060 % of the time • In the rest of the tests face could be detected for 95 % of the time • The software didn’t recognized standing up event • Face was already lost

Discussion • Measurement of sitting time could be accurate enough • Accuracy of the face tracking was unsatisfactory

Discussion • Absolute measurement by tracking the body and head from side http: //designer. mech. yzu. edu. tw/articlesystem/article/compressedfile/%282006 -0901%29%20 Chapter%202%20 Accelerometry%20 for%20 human%20 body%20 movement. as px? Arch. ID=1420

Thank you!