Development of an optical motion-capture system for 3D gait analysis

This work presents the development of an optical motion-capture system for 3D gait analysis. The system consists of two video cameras with speed of 25 fps, flash lighter, LED markers, and two PCs and technical computing software, which are used to acquire marker motion attached to human body during walking. The developed system has five module to obtain real coordinate of markers, i.e. pre-processing, camera calibration, marker detection and tracking, 3D reconstruction, and post-processing module. In the experiment, two camcorders are synchronized using flashlight. The recorded videos from experiment are extracted into frames. The synchronized framesare converted into binary images and marker position can be detected and tracked using least distance method. 3D Direct Linear Transformation method has been used to reconstruct 3D marker position in real coordinate. The marker positions data obtained from experiment could then be used for further kinematics and kinetics analysis of human gait.