Marker tracking systems add special patterns to the scene.
The main inconvenience is the environment adaptation,
although in some cases, this adaptation is feasible and does not involve any obstacle at all
Besides the environment adaptation,
fiducial marker occlusion is another shortcoming
as the system fails even if the marker is only slightly occluded.
To overcome the occlusion problem, much effort has been made to obtain an accurate and robust tracking system based on computer vision.
The approach presented in [16] places multiple markers in the scene to solve the marker occlusion problem.
In the same way, authors proposed multiple-layer markers in [17].
Another alternative solution was presented in [15],
where a new marker design consisted of adding customized textured borders to the marker.