Frame-difference analysis of video-recorded laser-beam projections

Laser beams have been applied in many human motion research contexts to project movements in specific motor tasks. Currently, there are no objective analysis methods for laser projection recordings. The principal aim of this study was to investigate the feasibility of quantifying motion by applying frame differencing and image analysis methods to video streams of laser beam projections. The laser projection was controlled by a mechanical device that produced pseudo random rotations. The 2D motion recorded by the video was compared with recordings obtained with an electromagnetic system where a sensor was fixed to the same device as the laser. High correlations in the time and frequency domains were found between the methods. We conclude that the proposed method can accurately quantify complex motion patterns from laser beam projections.