Transitions between body-locked and world-locked augmented reality

A head-mounted display device comprising:

• an inertial measurement unit (IMU) configured to determine an orientation of the head-mounted display device in three degrees of freedom;
• an optical sensor configured to capture image data of a real-world environment and cooperate with the IMU to determine a location and the orientation of the head-mounted display device in six degrees of freedom;
• a see-through display through which a real-world environment is viewable by a wearer, the see-through display being configured to display virtual objects to the wearer such that virtual objects appear to be integrated with the real-world environment, the see-through display being configured to:
• responsive to a transition from tracking the orientation of the head-mounted display device in three degrees of freedom to tracking the location and the orientation of the see-through display in six degrees of freedom, display via the see-through display one or more virtual objects with a world-locked position in which a position of each virtual object appears to be fixed relative to real-world objects viewable through the see-through display and the position of each virtual object appears to be moveable relative to a wearer of the see-through display, the world-locked position being derived from the location and orientation of the head-mounted display device in six degrees of freedom;
• and
• responsive to a transition from tracking the location and the orientation of the head-mounted display device in six degrees of freedom to tracking the orientation of the see-through display in three degrees of freedom, displaying via the see-through display the one or more virtual objects with a body-locked position in which the position of each virtual object appears to be fixed relative to the wearer of the see-through display and the position of each virtual object appears to be moveable relative to the real-world objects, the body-locked position being derived from the orientation of the head-mounted display device in three degrees of freedom.