Light-weight passive reflective markers made from polystyrene hemispheres covered in special retro-reflective material. These markers in different sizes and shapes can be used, for instance, to measure a limb displacement value of a running animal. Markers are made of polystyrene hemispheres covered in special retro-reflective tape also used on running shoes to make them shine in the light from car headlights - attach them to an animal to improve video tracking performance.
The reflective markers are particular helpfull for motion analysis systems based on contrast like LoliTrack, since they will appear as bright white dots in contrast to the surroundings when viewed from any angle. Perfect results can be made with a CCD camera and the use of an infra-red light source.