Movement detection in low light environments

A method for tracking movements of a head-mounted device (HMD) in a low light environment, the method being performed by the HMD, the method comprising:

• detecting the presence of a low light environment;
• emitting a flood of infrared (IR) light from a flood IR light illuminator that is mounted on the HMD in response to detecting the presence of the low light environment;
• detecting reflected IR light generated as a result of a least a portion of the flood of IR light reflecting off of a surface in the low light environment, wherein the reflected IR light is detected by a head-tracking stereo camera pair that includes a first camera and a second camera, the first camera and the second camera being mounted on the HMD, and wherein the first camera and the second camera are configured to detect both visible light and IR light;
• and
• based on the detected reflected IR light, determine a position of the HMD.

A method for tracking a position of a head-mounted device (HMD) within a surrounding environment, the method comprising:

• emitting a flood of infrared (IR) light from a flood IR light illuminator that is mounted on the HMD, the flood of IR light being emitted at an illumination intensity into the surrounding environment and which results in reflected IR light being reflected from one or more objects in the surrounding environment;
• capturing an image of the reflected IR light with a camera system mounted to the HMD;
• identifying a quantity of anchor points in the captured image;
• and
• modifying the illumination intensity by increasing or decreasing a power supplied to the flood IR light illuminator to alter the quantity of anchor points that are detected in a subsequent image captured by the camera system and until the quantity of anchor points that are detected is a predetermined quantity of anchor points.