Position estimation using predetermined patterns of light sources

A non-transitory computer-readable medium having program instructions stored thereon that are executable by at least one processor, the program instructions comprising:

• instructions for receiving infrared (IR) image data of an eye, wherein the infrared image data is recorded by an imaging device that is associated with a head-mountable display (HMD), wherein three or more IR light sources are arranged to reflect light off the eye, wherein the IR light sources are switched on and off according to a predetermined pattern while the infrared image data is being recorded, and wherein the predetermined pattern is such that one of the IR light sources is switched off during the recording of any given frame of the infrared image data;
• instructions for subtracting a first frame of the IR image data from a second frame of the IR image data to determine a first frame difference;
• and
• instructions for analyzing the first frame difference to determine at least one location for a first glint corresponding to a first one of the IR light sources, wherein the first IR light source is switched off during the first frame and is switched on during the second frame.

A system comprising:

• at least one processor;
• a non-transitory computer-readable medium;
• and
• program instructions stored on the non-transitory computer-readable medium and executable by the at least one processor to cause the system to:
• receive infrared (IR) image data of an eye, wherein the infrared image data is captured by imaging device that is associated with a head-mountable display (HMD), wherein three or more IR light sources are arranged to reflect light off the eye, wherein the IR light sources are switched on and off according to a predetermined pattern while the infrared image data is being recorded, and wherein the predetermined pattern is such that one of the IR light sources is switched off during the recording of any given frame of the infrared image data;
• subtract a first frame of the IR image data from a second frame of the IR image data to determine a first frame difference;
• and
• analyze the first frame difference to determine at least one location for a first glint corresponding to a first one of the IR light sources, wherein the first IR light source is switched off during the first frame and is switched on during the second frame.