Phone case for tracking and localization

A machine comprising:

• at least one processor;
• and
• at least one memory storing instructions that, when executed by the at least one processor, cause the machine to perform operations comprising:
• determining, by the head-worn device, a first relative pose between the head-worn device and the portable device using visual-inertial odometry (VIO)-based tracking;
• determining, by the head-worn device, a second relative pose between the head-worn device and the portable device by capturing an image including representations of the light sources and extracting positions of the light sources in the image;
• determining a drift during the VIO-based tracking based on the first relative pose and the second relative pose;
• adjusting subsequent VIO-based tracking based on the drift;
• and
• determining a recalibration frequency for determining the drift based on a power savings for the head-worn device and an accuracy of user interface interactions.

A machine-storage medium including instructions that, when executed by a machine, cause the machine to perform operations comprising:

• determining, by the head-worn device, a first relative pose between the head-worn device and the portable device using visual-inertial odometry (VIO)-based tracking;
• determining, by the head-worn device, a second relative pose between the head-worn device and the portable device by capturing an image including representations of the light sources and extracting positions of the light sources in the image;
• determining a drift during the VIO-based tracking based on the first relative pose and the second relative pose;
• adjusting subsequent VIO-based tracking based on the drift;
• and
• determining a recalibration frequency for determining the drift based on a power savings for the head-worn device and an accuracy of user interface interactions.