Inside-Out tracking

Inside-Out tracking is a method of positional tracking commonly used in XR technologies, specifically for tracking the position of head-mounted displays (HMDs) and motion controller accessories. It differentiates itself from outside-in tracking by the location of the cameras or other sensors that are used to determine the object’s position in space.
For inside-out positional tracking, the camera or sensors are located on the device being tracked (e.g., an HMD) while for outside-out positional tracking, the sensors are placed in stationary locations. An XR device using inside-out tracking looks out to determine how its position changes in relation to the environment. When the headset moves, the sensors readjust the user’s place in the room and the virtual environment responds accordingly in real-time. This type of positional tracking can be achieved with or without markers placed in the environment. The latter is called markerless inside-out tracking.