Simple method integrating OpenPose and RGB-D camera for identifying 3D body landmark locations in various postures

Abstract

Ergonomic assessments of posture are indispensable for reducing the risk of physical discomfort in the workplace. However, it is challenging to measure postural data in field studies because of the high cost and complex setup required by conventional motion tracking systems. OpenPose is an advanced approach for real-time multi-person two-dimensional (2D) pose estimations in an image, whereas RGB-D cameras can simultaneously record image and depth data. Thus, the present study proposes integrating these two approaches to identify 3D body landmark locations. To quantify the accuracy of the proposed method, the anatomical body landmark locations identified by a marker-based reference system were used as a gold standard. The tracking errors of using two RGB-D cameras, which used different data acquisition techniques (stereoscopic and time-of-flight (ToF)), were examined and compared. Thirty participants were recruited to perform 15 static postures. The average tracking errors of the landmark locations were 7.96 ± 3.59 and 9.81 ± 5.57 cm (stereoscopic), and 6.38 ± 2.88 and 8.18 ± 5.56 cm (ToF) for the standing postures and sitting postures, respectively. Depending on the desired accuracy, the integration of the RGB-D cameras and OpenPose could provide an alternative motion tracking method to identify 3D body landmark locations in a simple manner when postural assessments are performed.