A flexible high-precision video system for digital recording of motor acts through lightweight reflex markers

This paper describes and evaluates the digital MacReflex system for wireless recording of movements in three dimensions. Up to seven high resolution infra-red sensitive CCD video cameras with electronic shutters register the positions of maximally 40 stroboscopically illuminated retro-reflective tape markers. The system is equipped with real-time video processors for computation of position co-ordinates for the markers and for optimised data transmission and storage. Data are output to any type of computer through a standard serial interface, which also provides possibilities for simultaneous A/D-sampling. Dynamic manipulation of the recorded signals in three-dimensional plots is provided by standard software and transformation and evaluation of recorded data are performed in standard software. The described equipment is found to offer a flexible and easily operated solution for recording of movements with high resolution.