EFFECTS OF VIEWING ANGLE ON THE ESTIMATION OF JOINT ANGLES IN THE SAGITTAL PLANE

摘要

In assessing risks related to working posture, pictures of postures are taken from various directions, which can be a source of observation error. Joint postures of the neck, low back, knee, shoulder, and elbow were taken from 7 different viewing angles and 19 observers estimated joint angles after observing the pictures in 2-dimensional display. The joint angles were also measured using an optoelectronic motion measurement system. The estimation error increased as the viewing angles increased, but the patterns differ according to which joint angles were being observed. In general, it is strongly recommended to maintain the viewing angle within 40 degrees from the sagittal plane, while taking pictures of postures from the behind the individual is least recommended.