Patent Publication Number: US-2023147801-A1

Title: Systems and methods for facial expression tracking

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority under 35 U.S.C. § 120 as a continuation of U.S. Non-Provisional Pat. Application No. 16/746226, filed on Jan. 17, 2020, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to a facial tracking system. More particularly, the present disclosure relates to systems and methods tracking facial expressions. 
     BACKGROUND 
     The present disclosure relates generally to facial tracking systems. Facial tracking systems or devices may be utilized in a variety of electronic devices. For example, a facial tracking system may be utilized to determine a facial expression on a face of a user of a virtual reality (VR), augmented reality (AR), or mixed reality (MR) system. 
     SUMMARY 
     The subject matter of this disclosure is directed to systems and methods for facial expression tracking. In some embodiments, the system includes an illuminator, a single or group of photon detectors, one or more analog circuits, and/or a software algorithm to reconstruct facial expressions based on the information from the photon detectors. In some embodiments, the photon detectors and/or the illuminators do not require lenses. The system provides a low cost, low computational overhead facial recognition system that does not require cameras or complex image data processing in some embodiments. 
     One implementation of the present disclosure is related to a wearable display (e.g. a head mounted (HMD)), according to some embodiments. The wearable display may include an element configured to be worn on a head of a user, an illuminator disposed with the element and configured to emit light toward at least a portion of the head, a photon detector disposed with the element and configured to receive light reflected from at least a second portion of the head, and one or more processors coupled to a non-transitory computer-readable storage medium having instructions encoded thereon that, when executed by the one or more processors, cause the one or more processors to cause the illuminator to project the light toward the portion of the head , receive information from the photon detector, and determine a facial expression of the user based at least on the information from the photon detector. In some embodiments, the element is a glass frame and/or a housing. 
     In another implementation, a facial tracking system includes an illuminator configured to emit light toward at least a portion of a face of a user, a photon detector configured to receive light reflected from at least a second portion of the face, and a processor. The processor is configured to receive information regarding the characteristics of light detected by the photon detector, and determine a facial expression of the face based on the characteristics of light detected by the photon detector. 
     In another implementation, a method of facial tracking includes projecting light using an illuminator of a facial tracking system toward a face of a user, receiving, at the processor, information from a photon detector, the information comprising characteristics of the light reflected from the face, and determining, via the processor, a facial expression of the face based on the information from the photon detector. 
     These and other aspects and implementations are discussed in detail below. The foregoing information and the following detailed description include illustrative examples of various aspects and implementations, and provide an overview or framework for understanding the nature and character of the claimed aspects and implementations. The drawings provide illustration and a further understanding of the various aspects and implementations, and are incorporated in and constitute a part of this specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are not intended to be drawn to scale. Like reference numbers and designations in the various drawings indicate like elements. For purposes of clarity, not every component can be labeled in every drawing. In the drawings: 
         FIG.  1    is a block diagram of a facial tracking system in accordance with an illustrative embodiment. 
         FIG.  2    is a view of a user wearing a head mountable device integrated with a facial tracking system is shown.in accordance with an illustrative embodiment. 
         FIG.  3    depicts an example of a facial tracking device in accordance with an illustrative embodiment. 
         FIG.  4    depicts an example of a facial tracking device in accordance with an illustrative embodiment. 
         FIG.  5    depicts a diagram of a facial tracking device detecting an object in accordance with an illustrative embodiment. 
         FIG.  6    depicts a diagram of a facial tracking system in accordance with an illustrative embodiment. 
         FIG.  7    depicts a block diagram of circuitry of a facial tracking system in accordance with an illustrative embodiment. 
         FIG.  8    depicts an example of a facial tracking device in accordance with an illustrative embodiment. 
         FIG.  9    depicts an example of a facial tracking device in accordance with an illustrative embodiment. 
         FIG.  10    depicts a diagram of a facial tracking system in accordance with an illustrative embodiment. 
         FIG.  11    depicts a schematic diagram of a winner take all circuit and example outputs in accordance with an illustrative embodiment. 
         FIG.  12    depicts a flow diagram of a method of facial tracking in accordance with an illustrative embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring generally to the FIGURES, systems and methods for a facial tracking systems are shown, according to some embodiments. The facial tracking system includes a facial tracking circuit. The facial tracking circuit includes an illuminator and a photon detector. In some embodiments, the facial tracking circuit includes two or more illuminators or photon detectors. In some embodiments, the facial tracking system includes a first facial tracking circuit positioned to monitor a first portion of a face of a user and facial tracking circuit positioned to monitor a second portion of the face of the user. In some embodiments, the facial tracking system may include additional facial tracking circuits, each configured to monitor respective portions of the face of the user. In some embodiments, a first illuminator is configured to project a light toward a first portion of the face (e.g., a right side of a mouth of the user) of a user and a first detector is configured to receive the light reflected from the first portion of the face and a second illuminator is configured to project a second light toward a second portion of the face of the user (e.g., a left side of a mouth of the user) and a second detector is configured to receive the second light reflected from the second portion of the face. The light received at the first detector and the second light received at the second detector may then be used to determine a distance that the respective portions of the face are from the detector. The facial tracking system may then determine that the user is making a facial expression (e.g., a smile, frown, excitement, surprise, etc.) based on the known portions of the face that the first and second detectors are receiving the respective light from. In this way, the facial tracking system may track the facial expressions of a user with one or more illuminators and photon detectors, which may reduce the facial tracking system’s processing requirements and/or footprint. In other words, the facial tracking system provides for a low cost, low computational overhead facial recognition system that does not require cameras or complex image data processing. 
     In some embodiments, the facial tracking system may be implemented in various form factors. For example, the facial tracking system may be implemented in the form of worn device such as a head mountable device or other device that is positioned to monitor a face of a user. In some embodiments, the worn device may include glasses, goggles, or other head wearable device. Further, the facial tracking system may be implemented or connectable to various electronic devices. For example, the facial tracking system may be implemented with a virtual reality (VR) system, augmented reality (AR) system, or mixed reality (MR) system. In some embodiments, the facial tracking system may be implemented with electronic devices such as game consoles, server systems, personal computers, or gaming systems. 
     Referring now to  FIG.  1   , a block diagram of a facial tracking system  100  is shown. The facial tracking system  100  may include a facial tracking device  101 , and processing circuitry  102 . The facial tracking device  101  includes an illuminator  110  and a photon detector  111 . In some embodiments, the facial tracking device  101  may include two or more illuminators  110  and/or two or more photon detectors  111 . In some embodiments, the illuminator  110  may include an infrared illuminator, diode, light emitting diode (LED), lamp, laser, a combination thereof, or other illumination sources. Additionally, the photon detector  111  may include photoconductive detectors, photovoltaic detectors, p-n junction photovoltaic detectors, p-i-n photodiodes, avalanche photodiodes (APD), Schottky photodiodes, photo-electromagnetic (PEM) detectors, quantum well infrared photodetectors (QWIP), a combination thereof, or other types of photon detectors. The illuminator  110  is positioned or arranged to project a light toward a first portion of a face of a user, and the photon detector  111  is positioned or arranged to receive light reflected from the first portion of the face of the user. In this way, the facial tracking system  100  may monitor movements and/or detect positions of objects within the first portion. In some embodiments, the facial tracking system  100  and/or facial tracking device  101  is part of a game console, a VR, AR, or MR console, or a wearable display. 
     The processing circuitry  102  may include a processor  120 , a memory  121 , and an input/output interface  122 . In some embodiments the processing circuitry  102  may be integrated with various electronic devices. For example, in some embodiments, the processing circuitry  102  may be integrated with a wearable device such as a head worn display, smart watch, wearable goggles, or wearable glasses. In some embodiments, the processing circuitry  102  may be integrated with a gaming console, personal computer, server system, or other computational device. In some embodiments, the processing circuitry  102  may also include one or more processors, application specific integrated circuit (ASICs), or circuity (e.g., such as winner take all circuitry) that are integrated with the facial tracking device  101  and are designed to cause or assist with the facial tracking system  100  in performing any of the steps, operations, processes, or methods described herein. 
     The processing circuitry  102  may include one or more circuits, processors  120 , and/or hardware components. The processing circuitry  102  may implement any logic, functions or instructions to perform any of the operations described herein. The processing circuitry  102  can include memory  121  of any type and form that is configured to store executable instructions that are executable by any of the circuits, processors or hardware components. The executable instructions may be of any type including applications, programs, services, tasks, scripts, libraries processes and/or firmware. In some embodiments, the memory  121  may include a non-transitory computable readable medium that is coupled to the processor  120  and stores one or more executable instructions that are configured to cause, when executed by the processor  120 , the processor  120  to perform or implement any of the steps, operations, processes, or methods described herein. In some embodiments, the memory  121  is configured to also store, within a database, information regarding the type, form, or characteristics of the light that each illuminator  110  is able to or configured to emit and the positions, portions, or objects that each photon detector  111  is configured to or arranged to monitor or detect. The processing circuitry  102  can include converters, signal processing circuits, filters, and other interface elements in the analog domain and/or the digital domain. 
     In some embodiments, input/output interface  122  of the processing circuitry  102  is configured to allow the processing circuitry  102  to communicate with the facial tracking device  101  and other devices. In some embodiments, the input/output interface  122  may be configured to allow for a physical connection (e.g., wired or other physical electrical connection) between the processing circuitry  102  and the facial tracking device  101 . In some embodiments, the input/output interface  122  may include a wireless interface that is configured to allow wireless communication between the facial tracking device  101  (e.g., an ASIC, integrated circuit (IC), or processor on the facial tracking device  101  connected to the illuminator  110  and the photon detector  111 ) and the processing circuitry  102 . The wireless communication may include a Bluetooth, wireless local area network (WLAN) connection, radio frequency identification (RFID) connection, or other types of wireless connections. In some embodiments, the input/output interface  122  also allows the processing circuitry  102  to connect to the internet (e.g., either via a wired or wireless connection). In some embodiments, the input/output interface  122  also allows the processing circuitry  102  to connect to other devices such as a display, audio system, multiple facial tracking devices  101 , or other devices. 
     It should be noted that various other components can be included in the facial tracking system  100  that are not shown for sake of clarity of the present embodiments. These can include various power and/or signal conditioning components such as analog to digital converters, multiplexers, transistors, etc. Such additional components can be included in either the facial tracking device  101  or the processing circuitry  102  as appropriate for the particular embodiment. 
     Referring now to  FIG.  2   , a view  200  of a user wearing a head mountable device integrated with a facial tracking system is shown. The view  200  depicts a user  201  having a wearable device  202  (e.g., a head mounted devise affixed to a head  203  of the user). The wearable device  202  includes a facial tracking system  204 . The facial tracking system  204  may be similar to, or implemented as, the facial tracking system  100  described in reference to  FIG.  1   . 
     The facial tracking system  204  includes a first facial tracking device  240  and a second facial tracking device  245 . The first facial tracking device  240  is positioned or arranged on or within the wearable device  202  such that the first facial tracking device  240  is configured to monitor or detect movements or positions of objects (e.g., a right side of a mouth  230  of the user  201 ) within, at, or along a first portion  290  of the head  203 . Additionally, the second facial tracking device  245  is positioned or arranged on or within the wearable device  202  such that the second facial tracking device  245  is configured to monitor or detect movements or positions of objects (e.g., a left side of the mouth  230  of the user  201 ) within, at, or along a second portion  295  of the head  203 . In some embodiments, fewer or additional facial tracking devices  240  and  245  may be implemented depending upon particular applications. 
     In some embodiments, the first facial tracking device  240  is mounted to a first side of the wearable device  202  such that the first facial tracking device  240  is arranged to be positioned on a first side of a nose  231  of the user and the second facial tracking device  245  is mounted to a second side of the wearable device  202  such that the second facial tracking device  245  is arranged to be positioned on a second side of the nose  231 . In this way, the facial tracking system may be able to monitor a greater amount of area of the head  203  of the user  201  without having obstructions from the nose  231  or other facial features. 
     The first facial tracking device  240  includes a first illuminator  110   a  and a first photon detector  111   a . In some embodiments, the first facial tracking device  240  may include more than one illuminator  110   a  and/or more than one photon detector  111   a . The first illuminator  110   a  is configured to project or emit a first light at least toward the first portion  290  and the first photon detector  111   a  is configured to receive light reflected from the first portion  290 . The reflected first light may then be used to calculate, determine, or estimate a distance of objects within the first portion  290  from the first facial tracking device  240 . For example, the reflected light is received by the photon detector  111   a  and the photon detector  111   a  generates a corresponding electrical signal that is indicative of the characteristics of the reflected light. In some embodiments, the electrical signal is indicative of the intensity of the light received (e.g., a higher current is generated by the photon detector in response to receiving a more intense light). The facial tracking system  204  (e.g., processing circuitry  102 ) may cross-reference within a database or use a formula that relates distance to the intensity of light received by the photon detector  111   a  to an estimated distance of objects within the first portion  290  from the first facial tracking device  240 . In some embodiments, the database or formula may be unique to the type of illuminator  110   a  and photon detector  111   a  used and pre-stored within memory of the processing circuitry  102 . 
     The second facial tracking device  245  also includes a second illuminator  110   b  and a second photon detector  111   b . In some embodiments, the second facial tracking device  245  may include more than one illuminator  110   b  and/or more than one photon detector  111   b . The second illuminator  110   b  is configured to project or emit a second light at least toward the second portion  295  and the second photon detector  111   b  is configured to receive light reflected from the second portion  295 . The reflected second light may then be used to calculate, determine, or estimate a distance of objects within the second portion  295  from the second facial tracking device  245 . For example, the reflected light is received by the second photon detector  111   b  and the photon detector  111   b  generates a corresponding electrical signal that is indicative of the characteristics of the reflected light. In some embodiments, the electrical signal is indicative of the intensity of the light received (e.g., a higher current is generated by the photon detector in response to receiving a more intense light). The facial tracking system  204  may cross-reference within a database or use a formula that relates distance to the intensity of light received by the second photon detector  111   b  to an estimated distance of objects within the second portion  295  from the second facial tracking device  245 . In some embodiments, the database or formula may be unique to the type of illuminator  110   b  and photon detector  111   b  used and pre-stored within memory of the processing circuitry  102 . 
     In some embodiments, the facial tracking system  204  also includes processing circuitry  102 , an integrated circuit (IC), or an ASIC that is at least partially housed within the head mountable device  202 . In some embodiments, the processing circuitry  102  also includes processors, memory, or machine readable medium that are located within auxiliary devices such as server systems, smartphones, personal computers, or devices that are supplementary to the head mountable device  202 . The processing circuitry  102  is communicably coupled to and configured to control the facial tracking devices  240  and  245 . For example, the processing circuitry  102  is communicably coupled to and configured to control the first illuminator  110   a  and the second illuminator  110   b  and is communicably coupled to and configured to receive data (raw data, processed data, conditioned data, or otherwise) from the first photon detector  111   a  and the second photon detector  111   b . 
     References to both  FIGS.  3  and  4    are made in tandem for purposes of demonstration.  FIG.  3    depicts an example of a facial tracking device  300 .  FIG.  4    depicts a second example of a facial tracking device  400  is shown. The examples of the facial tracking device  300  and  400  include an illuminator  110  and an array of detectors  301 . In some embodiments, the illuminator  110  and the array of detectors  301  are mounted to or within a substrate  302 . The substrate  302  may be a portion of a head mountable device (e.g., such as wearable device  202  as described in reference to  FIG.  2   ). In some embodiments, the substrate  302  may be a rigid material such as a plastic, metal, composite, fiberglass, or a combination thereof that is configured to be mechanically affixed selectively or permanently to a respective device such as a head mountable device. In some embodiments, the substrate  302  may also have one or more portions of processing circuitry  102  mounted thereto or within. 
     The array of detectors  301  include multiple detectors  111   a - h  that enhance the resolution of the facial tracking device  300  or  400  to monitor or detect one or multiple objects within a respective area (e.g., such as the first portion  290  or the second portion  295  as described in reference to  FIG.  2   ). For example, the illuminator  110  may be selectively controlled to project a light toward, over, or throughout a first area of a head of a user and each of the multiple detectors  111   a - h  are arranged and configured to receive portions of the light reflected from objects within respective portions of the first area. The light received by each of the multiple detectors  111   a - h  may then be processed or used to determine a landscape or facial expression of the first area. 
     The exact configuration of the array of detectors  301  (e.g., or number of multiple detectors  111   a - h  within the array of detectors  301 ) may depend upon the particular application or wearable device that the respective facial tracking device  300  or  400  is to be integrated with. For example, now referring to  FIG.  3   , in some embodiments, the multiple detectors  111   a - h  may be arranged linearly. In such an example, the multiple detectors  111   a - h  may allow for the facial tracking device  300  to monitor or detect positions of objects along an axis of a first area. In another example, now referring to  FIG.  4   , the multiple detectors  111   a - h  may be arranged along rows and columns. In such an example, the multiple detectors  111   a - h  may allow for the facial tracking device  400  to monitor or detect positions of objects along a first axis and a second axis of a first area. 
     In some embodiments, more than one illuminator  110  may be used with the array of detectors  301 . In some embodiments, the multiple detectors  111   a - h  may include 2, 3, 4, 5, 6, 7, 8, 9, 10 or more detectors. In some embodiments, the multiple detectors  111   a - h  may be arranged in a circle, square, randomly, or any shape that allows for the multiple detectors  111   a - h  to enhance a resolution of a respective area. In some embodiments, each of the multiple detectors  111   a - h  may be configured to receive light reflected from a respective portion of an area where the respective portions do not overlap. In some embodiments, each of the multiple detectors  111   a - h  may be configured to receive light reflected from a respective portion of an area where one or more of the respective portions do overlap. 
     Referring now to  FIG.  5   , a diagram  500  of a facial tracking device detecting an object is shown. The diagram  500  includes a facial tracking device  501  detecting or monitoring an object  504 . The facial tracking device  501  includes an illuminator  110  and a photon detector  111 . In some embodiments, the object  504  may include a facial feature such as a portion of the brow, mouth, nose, or chin of a user. 
     The illuminator  110  is configured to emit or project a light over a first area  503  of the object  504 . The detector  111  is configured to receive portions of the light reflected from a second area  502  of the object. In some embodiments, the first area  503  and the second area  504  are the same. In some embodiments, the first area  503  is larger and includes the second area  504 . The detector  111  may then receive the portions of the reflected light and the characteristics of the reflected light (e.g., phase, flight time, intensity, frequency, etc.) may then be used to determine a distance that the object within the second area  504  is from the facial tracking device  501  (e.g., the detector  111 ). In some embodiments, the facial tracking device  501  continuously or discretely in a periodic pre-determined frequency monitors or detects (e.g., projects and receives reflected light) the object within the second area  504 . In some embodiments, multiple facial tracking devices are used to monitor multiple areas of the object  504 . In some embodiments, the illuminator is configured to or controlled to emit the light at a pre-determined frequency (e.g., in an infrared frequency). The pre-determined frequency may be selected to reduce possible interference from other sources. For example, a pre-determined frequency in the infrared range may reduce the likelihood that other light (e.g., not from the illuminator) may interfere with the reflected light received by the photon detectors  111 . In some embodiments, time division multiplexing may be used to reduce possible interference from more than one illuminators. As an example, when there are more than one illuminators, each illuminator may be turned on at a separate times in short bursts (e.g., a burst short enough in time such that a particular illuminator is not projecting light when its light is received by the photon detector) in order to reduce potential interference between the light from the more than one illuminators. In some embodiments, the time of flight between illumination and receiving the light at the photon detector may be used to calculate the distance of an object from the facial tracking device. In some embodiments, frequency division multiplexing may be used in order to reduce possible interference between light from other illuminators. For example, in some embodiments, each illuminator may be configured or controlled to project a light at a pre-determined frequency that is different than the other illuminators. 
     Referring now to  FIG.  6   , a diagram  600  of a facial tracking system is shown. The diagram  600  includes a facial tracking system  601 , a first example of a facial expression determination  602 , and a second example of a facial expression determination  603 . The facial tracking system  601  includes multiple facial tracking devices  611   a - h . A first set  611   a - d  of the multiple facial tracking devices are configured to be positioned (e.g., arranged on a substrate or head mountable device) on a first side (e.g., right side of a nose  640  of a user) of a head of a user and a second set  611   e - h  of the multiple facial tracking devices  611   a - h  are configured to be positioned on a second side of (e.g., left side of the nose  640 ) the head of the user. 
     Each of the multiple facial tracking devices  611   a - h  include an illuminator  110  and a photon detector  111  that are arranged and configured to monitor or detect a respective portion  612   a - h  of an object (e.g., a mouth  641  of a user). For example, a first facial tracking device  611   a  includes an illuminator  110  and a photon detector  111 . The illuminator  110  of the first facial tracking device  611   a  is arranged to project light toward a first area of the object that includes a first portion  612   a  of the object (e.g., the mouth  641 ) and the photon detector  111  is arranged to receive light reflected from the first portion  612   a . In this way, the multiple facial tracking devices  611   a - h  may be used to detect distances of the respective portions  612   a - h  of the object (e.g., a mouth  641 ). 
     The facial tracking device  601  may use the determined or detected distances of each portion  612   a - h  of the object to determine a facial expression of the user. That is, the facial tracking system  601  may map, interpolate, graph, or otherwise process the distances of each respective portion  612   a - h  to make a determination of a facial expression of the user. For example, the first facial detection device  611   a  detects that an outer portion ( 612   a ) of the mouth  641  is at a first distance and a fourth facial detection device  611   d  detects that a center portion ( 612   d ) is at a second distance. 
     In the first example of a facial expression determination  602 , facial tracking system  601  maps out, interpolates, graphs, or otherwise constructs an image of the object (e.g., mouth  641 ) based on the measured distances of each respective portion  612   a - h  and determines that the user is frowning. In some embodiments, the facial tracking system  601  may determine that the user is frowning based at least on the first distance being larger than the second distance by a pre-determined threshold. In some embodiments, the pre-determined threshold may be 0.5, 0.75, 1, 1.5, 2 or more centimeters. 
     In the second example of a facial expression determination  603 , facial tracking system  601  maps out, interpolates, graphs, or otherwise constructs an image of the object (e.g., mouth  641 ) based on the measured distances of each respective portion  612   a - h  and determines that the user is smiling. In some embodiments, the facial tracking system  601  may determine that the user is smiling based at least on the first distance being smaller than the second distance by a pre-determined threshold. In some embodiments, the pre-determined threshold may be 0.5, 0.75, 1, 1.5, 2 or more centimeters. In this way, the facial detection system  601  may monitor, detect, or determine a facial expression of a user without a camera or image processing, which reduces the amount of computational power needed. 
     Referring now to  FIG.  7   , a block diagram  700  of circuitry of a facial tracking system is shown. The block diagram  700  includes an array of detectors  701 , a multiplexer  702 , a demodulator  703 , an analog to digital converter (ADC)  704 , and a processing block  705 . The array of detectors  701  includes multiple photon detectors each connected to a respective terminal on the multiplexer  702 . The multiplexer  702  may have a respective address for each of the multiple detectors such that a processor (e.g., at the processing block  705 ) may be able to determine which signals are associated with each of the multiple detectors. The demodulator  703  is connected to the multiplexer  702  and configured to demodulate the signals generated by each of the multiple detectors. The ADC  704  is configured to convert the demodulated signals from the demodulator  703  into digital representations of the demodulated signals. The ADC  704  is connected to the processor (e.g., at the processing block) that is configured to process the digital representations of the demodulated signals to determine a facial expression of a user of the facial tracking system. For example, the processor may use the digital representations of the demodulated signals to determine a profile of objects (e.g., based on the distance of the objects sensed from each of the multiple photon detectors) based on the distances sensed by the array of detectors  701 . The processor may then determine based on the profile of the objects sensed by the array of detectors  702  the facial expression of the user (e.g., a smile, a frown, a scowl, a smirk, etc.). 
     References to both  FIGS.  8  and  9    are made in tandem for purposes of demonstration.  FIG.  8    depicts a third example of a facial tracking device  800 .  FIG.  9    depicts a fourth example of a facial tracking device  900  is shown. The examples of the facial tracking device  800  and  900  include an array of illuminators  801  and a photon detector  111 . In some embodiments, the array of illuminators  801  and photon detector  111  are mounted to or within a substrate  802 . The substrate  802  may be a portion of a head mountable device (e.g., such as wearable device  202  as described in reference to  FIG.  2   ). In some embodiments, the substrate  302  may be a rigid material such as a plastic, metal, composite, fiberglass, or a combination thereof that is configured to be mechanically affixed selectively or permanently to a respective device such as a head mountable device. In some embodiments, the substrate  802  may also have one or more portions of processing circuitry  102  mounted thereto or within. 
     The array of illuminators  801  include multiple illuminators  110   a - h  that are each spatially encoded or configured to emit spatially encoded light. The detector  111  is configured to receive light reflected from a first area of an object and each of the multiple illuminators  110   a - h  are configured to or arranged to project respective light toward respective portions of the first area of the object. In this way, the detector  111  receives light reflected from the first area that includes the spatially encoded light from at least some of the multiple illuminators  110   a - h . Corresponding circuitry and/or processing circuitry connected to the detector  111  may then receive data indicative of light received by the detector  111  and determine a facial expression of a corresponding user. For example, each of the multiple illuminators  110   a - h  may be configured to or controlled by a processor to emit light that is spatially encoded toward respective portions of an area of an object. The processor may have stored in a database the respective portion that each of the multiple illuminators are arranged to project light toward. Thus, the processing circuitry may control each of the multiple illuminators  110   a - h  such that each of them emit a light having a unique characteristic (e.g., frequency, intensity, etc.). The processing circuitry may then determine which portions of the light received by the detector  111  belong to the respective multiple illuminators  110   a - h  based at least on the unique characteristics in order to determine a distance the respective portions of the objects based on the spatially encoded light. 
     The array of illuminators  801  allows the facial tracking devices  800  or  900  to be used to map, interpolate, graph, or construct an image of an object using multiple illuminators and at least one detector. In other words, the array of illuminators  801  may allow for enhanced resolution of the facial tracking devices  800  or  900  in monitoring, detecting, or determining a distance profile of a respective area (e.g., such as the first portion  290  or the second portion  295  as described in reference to  FIG.  2   ). The exact configuration of the array of illuminators  801  (e.g., or number of multiple illuminators  110   a - h  within the array of illuminators  801 ) may depend upon the particular application or head mountable device that the respective facial tracking device  800  or  900  is to be integrated with. For example, now referring to  FIG.  8   , in some embodiments, the multiple illuminators  110   a - h  may be arranged linearly. In such an example, the multiple illuminators  110   a - h  may allow for the facial tracking device  800  to monitor or detect positions of objects along an axis of a first area. In another example, now referring to  FIG.  9   , the multiple illuminators  110   a - h  may be arranged along rows and columns. In such an example, the multiple illuminators  110   a - h  may allow for the facial tracking device  900  to monitor or detect positions of objects along a first axis and a second axis of a first area. 
     In some embodiments, more than one detector  111  may be used with the array of illuminators  801 . In some embodiments, the multiple illuminators  110   a - h  may include 2, 3, 4, 5, 6, 7, 8, 9, 10 or more illuminators. In some embodiments, each of the multiple illuminators  110   a - h  may be configured to project spatially encoded light toward respective portions of a first area where the respective portions do not overlap. In some embodiments, each of the multiple illuminators  110   a - h  may be configured to project spatially encoded light toward respective portions of a first area where one or more of the respective portions do overlap. In some embodiments, the respective portions are pre-determined or pre-measured and stored within a database. 
     Referring now to  FIG.  10   , a diagram of a facial tracking system  1000  is shown. The facial tracking system  1000  includes a first facial tracking device  1001  and a second facial tracking device  1002  both communicably coupled to processing circuitry  102 . The first facial tracking device  1001  is configured to be positioned (e.g., arranged on a substrate or head mountable device) on a first side (e.g., right side of a nose  1040  of a user) of a head of a user and the second facial tracking device  1002  is configured to be positioned on a second side of (e.g., left side of the nose  1040 ) the head of the user. 
     The first facial tracking device  1001  includes a first illuminator  110   a  and a first set of detectors  111   a - d . The first illuminator  110   a  is arranged and controlled by the processing circuitry  102  to project a light onto a first area of a head of a user. For example, the first area may include a right side of a mouth of the user. Each of the first set of detectors  111   a - d  are arranged to receive light reflected from respective portions of the first area. For example, a first detector  111   a  may be arranged to receive light reflected from a first portion of the first area that corresponds to an outer edge of a mouth of the user (e.g., an outer right edge of lips or mouth), a second detector  111   b  may be arranged to receive light reflected from a second portion of the first area that corresponds to a position of the mouth more center than the first portion, and a fourth detector  111   d  may be arranged to receive light reflected from a position that is near the center of the mouth (e.g., and/or near the center of the mouth on the same side of the mouth as the first portion). The second facial tracking device  1002  includes a second illuminator  110   b  and a second set of detectors  111   e - h . The second illuminator  1002  and the second set of detectors  111   e - h  may be arranged and configured to perform similar but symmetric operations on a second area of the head. For example, the second area may include the left side of the mouth. 
     Each of the detectors  111   a - h  are configured to receive light from reflected portions of a head in some embodiments. The exact position and or arrangements of each detector  111   a - h  and corresponding portions of the head may be known or determined and stored within a database. 
     Referring now to  FIG.  11   , a schematic diagram  1100  of a winner take all circuit  1101  and example outputs are shown. In some embodiments, a facial tracking system such as the facial tracking system  1000  described in reference to  FIG.  10    may determine a facial expression of a user in the analog domain. For example, a facial tracking system may use a winner take all circuit or similar circuit to determine a facial expression of a user based on an output of the circuit. 
     The schematic diagram  1100  includes a winner take all circuit  1101 . The winner take all circuit  1101  includes a first branch  1110  and a second branch  1111  each connected to a bias current source  1112 . In some embodiments, the winner take all circuit  1101  has as a branch for each one of the detectors  111  of a corresponding facial tracking device. Each branch includes a corresponding detector  110   a , a current source  1115 , a first transistor  1116 , and a second transistor  1117 . An output of the current source  1115  is connected to an output of the detector  110   a  and a first terminal of the first transistor  1116 . A second terminal of the first transistor  1116  is connected to ground. A control terminal (e.g., gate terminal) of the first transistor  1116  is connected to a first terminal of the second transistor  1117  and to an input terminal of the bias current source  1112 . A control terminal (e.g., a gate terminal of the second transistor  1117  is connected to the first terminal of the first transistor  1116 . A second terminal of the second transistor  1117  is connected to a processor of the processing circuitry  102 . In some embodiments, the second terminal of the second transistor  1117  is connected to a respective input of a multiplexer or other address specific device. 
     The winner take all circuit  1101  is configured to signal to the processor a detector that has the highest or most intense signal. The processing circuitry may then determine a facial expression of the user based on which of the branches (e.g., and corresponding detector) has the highest or most intense signal. For example, the highest or most intense signal may indicate that the respective detector has an object closer to the respective detector than any other of the diodes. Thus, referring now back to  FIG.  10   , if a branch that corresponds to the first diode  111   a  is outputting the signal, the processing circuitry may determine that the portion corresponding to the first diode  111   a  (e.g., the outer edge of the mouth) has the smallest distance. The processor may then determine that the facial expression of the user is a smile (e.g., because the outer edge of the mouth is higher or closer to the detectors than the center of the mouth.). 
     In some embodiments, each facial tracking device may be connected to a corresponding winner take all circuit  1101 . In some embodiments, two or more of the facial tracking devices may be connected to a corresponding winner take all circuit  1101 . The outputs of the winner take all circuits  1101  may be connected to a processor directly or via circuitry such as a multiplexer. The multiplexer may be configured to signal to the processing circuitry an address of the branch or branches that are outputting a signal. The processing circuitry may cross reference the address or branch location within a database to determine which position on the head that the address corresponds to and determine the facial expression based on the corresponding position of the head. For example, if a branch corresponding to the detectors  111   d  on one winner take all circuit is outputting a signal and a branch corresponding to the detector  111   e  on another winner take all circuit is outputting a signal, then the processor may determine that the facial expression of the user is a frown. 
     Referring now to  FIG.  12   , a flow diagram  1200  of a method of facial tracking is shown. In operation  1201 , the facial tracking system projects light, using an illuminator, toward a face of a user. In some embodiments, a processor connected to the one or more illuminators causes the one or more illuminators to each project a light. In some embodiments, the facial tracking system causes the one or more illuminators to each project a light toward respective portions of a head (e.g., face or mouth) of a user). In some embodiments, the facial tracking system causes each of the illuminators to project spatially encoded light toward respective portions of the head. In some embodiments, the facial tracking system causes each of the one or more illuminators to project light having the same characteristics toward respective portions of the head. In some embodiments, the respective portions may overlap with one another. In some embodiments, the respective portions may not overlap with another. 
     In operation  1202 , the facial tracking system receives data indicative of received light from one or more photon detectors. That is, the light reflected from the respective portions of the head is received by one or more photon detectors and the detectors generate electrical signals indicative of the received light. In some embodiments, the electrical signals are received by a winner take all circuit and the winner take all circuit outputs a signal to the processor. In some embodiments, the electrical signals are converted into digital form (e.g., via an ADC) and received by the processing circuitry. In some embodiments, additional processing of the electrical signals via analog and/or digital circuitry may occur before the electrical signals are received by the processing circuitry. 
     In operation  1203 , the facial tracking system reconstructs spatial information based on the data of the one or more photon detectors. That is, the processing circuitry reconstructs a profile of the face based on the electrical signals. The electrical signals are reconstructed to create the profile of the face. In some embodiments, such as when the processing circuitry receives a signal from a winner take all circuit, the processor determines which portion of the face is closest or nearest to a particular detector (e.g., based on an address of the signal associated with the particular detector). The processing circuitry then may cross reference within a database the particular detector (e.g., the address) with a location and a respective portion of the face that the particular detector is positioned to receive light from. In this way, the processing circuitry may reconstruct the profile of the face based on the signal. 
     In some embodiments, the facial tracking system may determine a distance of objects sensed by each of the detectors using the electrical signals. The distance of objects sensed by each of the detectors may be determined based on the intensity (e.g., intensity or magnitude of current) generated by the photon detector. The intensity or magnitude of the signal (e.g., current) generated by each of the photon detectors may then be cross-referenced or used within a formula of known intensities or magnitudes of the signal versus a distance of the object from the photon detector in order to determine the distances. The processing circuitry may then use the distances, known address of each of the detectors, and the known respective portions of the head that each of the detectors are configured to receive reflected light from to create a profile of the face. In some embodiments, the facial tracking system may receive a signal from a photon detector that includes received light from a portion of the head and reconstruct the profile of the face based on the characteristics of the light received by the photon detector (e.g., and encoded within the signal). For example, in an embodiment where multiple illuminators are used, each being configured to project spatially encoded light toward respective portions of the face, the photon detector may output a signal encoded with information of each spatially encoded light received by the photon detector and the processing circuitry may reconstruct a profile based on the signal and known characteristics and positioning of the spatially encoded light. 
     In operation  1204 , the facial tracking system determines a facial expression based on the reconstructed spatial information. In some embodiments, the processing circuitry uses the reconstructed profile to determine a facial expression on the face of the user. For example, in some embodiments, the profile may be a profile of a mouth of the user and the processing circuitry may determine that the profile indicates that the user is smiling, scowling, frowning, or smirking. In some embodiments, the profile bay be a profile of a brow or forehead of the user and the profile may indicate that the user is expressing a worried look, or an angry look based on the profile of the brow. 
     Having now described some illustrative implementations, it is apparent that the foregoing is illustrative and not limiting, having been presented by way of example. In particular, although many of the examples presented herein involve specific combinations of method acts or system elements, those acts and those elements can be combined in other ways to accomplish the same objectives. Acts, elements and features discussed in connection with one implementation are not intended to be excluded from a similar role in other implementations or implementations. 
     The hardware and data processing components used to implement the various processes, operations, illustrative logics, logical blocks, modules and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some embodiments, particular processes and methods may be performed by circuitry that is specific to a given function. The memory (e.g., memory, memory unit, storage device, etc.) may include one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage, etc.) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present disclosure. The memory may be or include volatile memory or non-volatile memory, and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present disclosure. According to an exemplary embodiment, the memory is communicably connected to the processor via a processing circuit and includes computer code for executing (e.g., by the processing circuit and/or the processor) the one or more processes described herein. 
     The present disclosure contemplates methods, systems and program products on any machine-readable media for accomplishing various operations. The embodiments of the present disclosure may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwired system. Embodiments within the scope of the present disclosure include program products comprising machine-readable media for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions. 
     The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” “comprising” “having” “containing” “involving” “characterized by” “characterized in that” and variations thereof herein, is meant to encompass the items listed thereafter, equivalents thereof, and additional items, as well as alternate implementations consisting of the items listed thereafter exclusively. In one implementation, the systems and methods described herein consist of one, each combination of more than one, or all of the described elements, acts, or components. 
     Any references to implementations or elements or acts of the systems and methods herein referred to in the singular can also embrace implementations including a plurality of these elements, and any references in plural to any implementation or element or act herein can also embrace implementations including only a single element. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements to single or plural configurations. References to any act or element being based on any information, act or element can include implementations where the act or element is based at least in part on any information, act, or element. 
     Any implementation disclosed herein can be combined with any other implementation or embodiment, and references to “an implementation,” “some implementations,” “one implementation” or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with the implementation can be included in at least one implementation or embodiment. Such terms as used herein are not necessarily all referring to the same implementation. Any implementation can be combined with any other implementation, inclusively or exclusively, in any manner consistent with the aspects and implementations disclosed herein. 
     Where technical features in the drawings, detailed description or any claim are followed by reference signs, the reference signs have been included to increase the intelligibility of the drawings, detailed description, and claims. Accordingly, neither the reference signs nor their absence have any limiting effect on the scope of any claim elements. 
     Systems and methods described herein may be embodied in other specific forms without departing from the characteristics thereof. Further relative parallel, perpendicular, vertical or other positioning or orientation descriptions include variations within +/-10% or +/-10 degrees of pure vertical, parallel or perpendicular positioning. References to “approximately,” “about” “substantially” or other terms of degree include variations of +/-10% from the given measurement, unit, or range unless explicitly indicated otherwise. Coupled elements can be electrically, mechanically, or physically coupled with one another directly or with intervening elements. Scope of the systems and methods described herein is thus indicated by the appended claims, rather than the foregoing description, and changes that come within the meaning and range of equivalency of the claims are embraced therein. 
     The term “coupled” and variations thereof includes the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent or fixed) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members coupled directly with or to each other, with the two members coupled with each other using a separate intervening member and any additional intermediate members coupled with one another, or with the two members coupled with each other using an intervening member that is integrally formed as a single unitary body with one of the two members. If “coupled” or variations thereof are modified by an additional term (e.g., directly coupled), the generic definition of “coupled” provided above is modified by the plain language meaning of the additional term (e.g., “directly coupled” means the joining of two members without any separate intervening member), resulting in a narrower definition than the generic definition of “coupled” provided above. Such coupling may be mechanical, electrical, or fluidic. 
     References to “or” can be construed as inclusive so that any terms described using “or” can indicate any of a single, more than one, and all of the described terms. A reference to “at least one of ‘A’ and ‘B’” can include only ‘A’, only ‘B’, as well as both ‘A’ and ‘B’. Such references used in conjunction with “comprising” or other open terminology can include additional items. 
     Modifications of described elements and acts such as variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations can occur without materially departing from the teachings and advantages of the subject matter disclosed herein. For example, elements shown as integrally formed can be constructed of multiple parts or elements, the position of elements can be reversed or otherwise varied, and the nature or number of discrete elements or positions can be altered or varied. Other substitutions, modifications, changes and omissions can also be made in the design, operating conditions and arrangement of the disclosed elements and operations without departing from the scope of the present disclosure. 
     References herein to the positions of elements (e.g., “top,” “bottom,” “above,” “below”) are merely used to describe the orientation of various elements in the FIGURES. The orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.