One disclosed example provides a computing device configured to receive from an image sensor of a head-mounted device environmental tracking exposures and handheld object tracking exposures, determine a pose of the handheld object with respect to the head-mounted device based upon the handheld object tracking exposures, determine a pose of the head-mounted device with respect to a surrounding environment based upon the environmental tracking exposures, derive a pose of the handheld object relative to the surrounding environment based upon the pose of the handheld object with respect to the head-mounted device and the pose of the head-mounted device with respect to the surrounding environment, and output the pose of the handheld object relative to the surrounding environment for controlling a user interface displayed on the head-mounted device.