Marker-based tracking
Marker-based tracking is a kind of spatial tracking that uses a camera, a fiducial marker, and image registration to work.
The goal of marker based tracking is to keep track of the pose of an object in its environment. For example, keeping track of the pose of a head-mounted display to accurately render an augmented reality scene on top of the real world.
It requires a physical thing to be put in the real world, like a ArUco marker.
Marker-based tracking may be simpler to implement than markerless tracking.
Marker-based tracking has the benefit of working in moving vehicles such as cars and trains, and in low gravity space or variable gravity situations without active compensation, such as during a rocket launch. This is because it does not have to use IMU data. It can be IMU-free.
A marker can be placed on a floor or a ceiling. A ceiling is a safe bet for a head-mounted display using marker based tracking because a ceiling usually has a clear line of sight from the top of a person's head.
A marker can be printed out using a standard printer.
MBT has the benefit of having easy multi-user capability, as long as both people have a camera line of sight to the same marker.
Hardware[edit]
Marker based tracking typically uses a CMOS or CCD sensor.
OpenCV is often used.
Theoretically, a depth sensor can be used with a marker made not of black and white squares, but specular and diffuse squares.