BACKGROUND 
       [0001]    A three dimensional (3D) range camera determines distances to features in a scene that it images and may provide the distances in a range image, also referred to as a 3D image, comprising three spatial coordinates for each of the features relative to an origin of coordinates located at the camera. An active illumination range camera provides range images of scenes that it images responsive to light reflected by features in the scene from light that the camera transmits to illuminate the scene. Typically, an active illumination range camera may illuminate a scene with structured or temporally modulated, optionally infrared (IR), light to acquire a range image of the scene. A range camera that illuminates a scene that it range images with structured light determines distances to features in the scene by triangulation to structures in the structured light that are reflected by the features. A range camera that illuminates a scene that it range images with temporally modulated light, determines round trip times for a temporal “marker” of the modulated light to travel from the camera to features in the scene and back to the camera. The camera, also referred to conventionally as a time of flight (TOF) range camera, uses the round trip time determined for a given feature in the scene and the speed of light to determine a distance to the given feature 
         [0002]    Whereas active illumination range cameras were originally relatively scarce and limited to technical, engineering, and scientific applications, active illumination range imaging technology has matured, and range cameras are frequent components of a continually expanding catalog of consumer products. Range cameras may be found not only in video game consoles, but laptop computers, workbooks, tablets, smartphones, and even wrist watches. 
       SUMMARY 
       [0003]    With the increase in the commercial popularity of range cameras, it is anticipated that various venues may periodically become crowded with many users attempting to simultaneously operate active illumination range cameras to range image scenes in, or from, the venue. And it is expected that when a venue becomes crowded with users operating active illumination range cameras, light transmitted by an active illumination range camera in the venue may interfere with operation of another of the active illumination range cameras operating in the venue. An aspect of an embodiment of the disclosure therefore relates to providing a system, hereinafter also referred to as a “camera synchronization system”, a “CAM-Sync system”, or “CAM-Sync”, configured to coordinate operation of active illumination range cameras operating in a same venue to reduce possible interference between the range cameras. A venue in which active illumination cameras might interfere with each other&#39;s operation may be referred to as an imaging neighborhood. 
         [0004]    In an embodiment, CAM-Sync comprises an optionally cloud based hub having a database comprising a list of active illumination range cameras subscribed to CAM-Sync, each subscriber camera identified by an ID and configured by a CAM-Sync mobile app (application software), optionally downloaded from the hub. The CAM-Sync app, configures an active illumination range camera in which it is installed to communicate with the hub when it is operating in a same imaging neighborhood with other CAM-Sync subscriber range cameras to establish a time division multiplexing (TDM) imaging mode of operation for the range cameras. The TDM imaging mode provides each camera with an exclusive imaging time slot for acquiring a range image so that at any one time, substantially only one of the range cameras in the imaging neighborhood operates to transmit light and acquire a range image of a scene. 
         [0005]    In an embodiment, range cameras subscribed to CAM-Sync provide the CAM-Sync hub with location based data that enables the hub to determine their respective geolocations. CAM-Sync may use the geolocations to determine when more than one range camera subscribed to CAM-Sync is located in a same imaging neighborhood. Upon making such a determination the CAM-Sync hub may implement a TDM imaging mode by transmitting “image-ON” signals to each of the range cameras at different times. In response to receiving the image-ON signals, the range cameras operate to transmit light and acquire range images of a scene or scenes at different times. In an embodiment, the CAM-Sync app in an active illumination range camera subscribed to CAM-Sync configures the camera to determine if another CAM-Sync active illumination range camera is operating in its imaging neighborhood. If a CAM-Sync camera determines that another CAM-Sync camera is operating in its neighborhood, the CAM-Sync cameras in the imaging neighborhood and the CAM-Sync hub cooperate to establish a wireless local area network (WLAN) over which the cameras may communicate to implement a TDM imaging mode so that no two of the range cameras in the imaging neighborhood operate to acquire a range image at substantially a same time. 
         [0006]    This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
     
    
     
       BRIEF DESCRIPTION OF FIGURES 
         [0007]    Non-limiting examples of embodiments of the disclosure are described below with reference to figures attached hereto that are listed following this paragraph. Identical features that appear in more than one figure are generally labeled with a same label in all the figures in which they appear. A label labeling an icon representing a given feature of an embodiment of the disclosure in a figure may be used to reference the given feature. Dimensions of features shown in the figures are chosen for convenience and clarity of presentation and are not necessarily shown to scale. 
           [0008]      FIG. 1A  schematically shows, a CAM-Sync active illumination range camera in an imaging neighborhood communicating with a CAM-Sync hub, in accordance with an embodiment of the disclosure; 
           [0009]      FIG. 1B  schematically shows the CAM-Sync active illumination range camera shown in  FIG. 1A  interacting with another CAM-Sync active illumination range camera in the imaging neighborhood to establish a WLAN and operate in a TDM imaging mode, in accordance with an embodiment of the disclosure; and 
           [0010]      FIG. 2  schematically shows a CAM-Sync hub controlling active illumination range cameras in a same imaging neighborhood to operate in a TDM imaging mode, in accordance with an embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    In the detailed description below, aspects of a CAM-Sync system comprising an, optionally cloud based, hub that facilitates establishment of a WLAN over which active illumination range cameras in a same imaging neighborhood communicate to operate in a TDM imaging mode in accordance with an embodiment of the disclosure are discussed with reference to  FIGS. 1A and 1B . By way of example, the imaging neighborhood schematically shown in the figures is a neighborhood of a lion enclave at a zoo.  FIG. 2  schematically shows a CAM-Sync in accordance with an embodiment of the disclosure operating to control a plurality of range cameras at the zoo to operate in a TDM operating mode. 
         [0012]    The active illumination range cameras shown in the figures are assumed by way of example to be gated time of flight (GT-TOF) range cameras. A GT-TOF range camera, optionally referred to as a GT-TOF camera, generates and transmits temporally modulated light in a form of a train of light pulses to illuminate a scene that it range images. Following transmission of each light pulse in the train of light pulses, the GT-TOF camera may gate ON for a short exposure period to register amounts of light from the light pulse that features in the scene reflect back to the camera. The GT-TOF camera uses an amount of reflected light that it registers for the reflected light from a given feature in the scene during the short exposure periods following the light pulses to determine a round trip time for the given feature. The GT-TOF cameras in the figures may be independent stand-alone devices or cameras comprised in any of various mobile devices, hereinafter also referred to as “mobile communication devices”, configured for communication over a wireless communication network. Mobile communication devices include by way of example, laptop computers, workbooks, tablets, smartphones, cameras, wrist watches, glasses and other wearable devices configured for wireless communication. By way of example, the GT-TOF cameras are assumed to be included in smartphones. 
         [0013]    In the discussion, unless otherwise stated, adjectives such as “substantially” and “about” modifying a condition or relationship characteristic of a feature or features of an embodiment of the disclosure, are understood to mean that the condition or characteristic is defined to within tolerances that are acceptable for operation of the embodiment for an application for which the embodiment is intended. Wherever a general term in the disclosure is illustrated by reference to an example instance or a list of example instances, the instance or instances referred to, are by way of non-limiting example instances of the general term, and the general term is not intended to be limited to the specific example instance or instances referred to. Unless otherwise indicated, the word “or” in the description and claims is considered to be the inclusive “or” rather than the exclusive or, and indicates at least one of, or any combination of more than one of items it conjoins 
         [0014]      FIG. 1A  schematically shows a visitor  21  at a zoo who has just activated a GT-TOF camera  31  optionally comprised in a smartphone to image a lion  29  at the zoo. GT-TOF camera  31  is subscribed to an optionally cloud based CAM-Sync system  50  configured to communicate with subscriber GT-TOF cameras via the internet, in accordance with an embodiment of the disclosure. CAM-Sync  50  optionally comprises a database  51  having a list of GT-TOF cameras subscribed to CAM-sync, and a server  52  that processes communications between CAM-Sync  50  and subscriber GT-TOF cameras, such as GT-TOF camera  31 , subscribed to CAM-Sync. GT-TOF camera  31  is configured by an app, a CAM-Sync app, optionally downloaded from CAM-Sync  50  to communicate with CAM-Sync  50  to exchange data, and optionally to receive control messages from CAM-Sync  50  and/or other GT-TOF cameras subscribed to CAM-Sync  50 , that control operation of the GT-TOF camera in a TDM imaging mode. 
         [0015]    GT-TOF camera  31  optionally comprises components that are shown greatly enlarged in an inset  230 . It is to be understood that discussion of the components and their operation with respect to GT-TOF camera  31  may apply similarly to other GT-TOF cameras schematically shown in  FIGS. 1B and 2 . GT-TOF camera  31  comprises an, optionally IR, light source  231 , a lens system represented by a lens  232 , and a photosensor  233  comprising pixels  234  on which lens system  232  images light received by the camera. A GT-TOF controller  235  in GT-TOF camera  31 , controls transmission of light pulse trains by the camera&#39;s IR light source  231  and gating ON the camera&#39;s photosensor  233  for exposure periods to image and acquire distances to features of a scene, such as lion  29 , that the camera range images. 
         [0016]    GT-TOF camera  31  may have a communication interface  236  comprising any of various wireless communication interfaces to enable the camera to access the internet and communicate with CAM-Sync  50  and/or to communicate in accordance with a wireless communication protocol directly on a peer to peer basis with other GT-TOF cameras subscribed to CAM-Sync  50 . By way of example, communication interface  236  may comprise at least one of or any combination of more than one of WiFi, WiFi direct, and/or blue tooth radio interface to facilitate wireless connection to the internet and CAM-Sync  50 , and to facilitate direct peer to peer wireless communication with other GT-TOF cameras subscribed to CAM-Sync  50 . GT-TOF camera  31  may also be configured to communicate with other subscriber GT-TOF cameras using acoustic signaling. 
         [0017]    An embodiment of controller  235  of GT-TOF camera  31  may comprise any electronic and/or optical processing and/or control circuitry, to provide and enable functionalities that the camera may require to support range imaging and/or communication with CAM-Sync  50  and other subscriber GT-TOF cameras. By way of example, GT-TOF camera  31  may comprise any one, or any combination of more than one of, a microprocessor, an application specific circuit (ASIC), field programmable array (FPGA) and/or system on a chip (SOC). The GT-TOF camera may comprise a memory having any electronic and/or optical circuitry suitable for storing data and/or computer executable instructions and may, by way of example, comprise any one or any combination of more than one of a flash memory, random access memory (RAM), read only memory (ROM), and/or erasable programmable read-only memory (EPROM). Assuming as noted above that GT-TOF camera  31  is comprised in a smartphone, imaging and communication functionalities of GT-TOF camera  31  may be supported by processor and memory circuitry comprised in the smartphone that support smartphone functionalities. 
         [0018]    Upon being turned on to acquire a range image, GT-TOF camera  31  is configured to transmit a sign-in message to CAM-Sync  50  advising that it has been turned on, provide CAM-Sync  50  with an ID of the GT-TOF camera, and transmit data to CAM-Sync  50  defining the camera&#39;s geolocation. In an embodiment, the ID code transmitted by a GT-TOF camera  31  is an international mobile subscriber identity (IMSI) code of the subscriber identity module (SIM) in the smartphone that comprises the GT-TOF camera. Optionally, upon receipt of the ID code CAM-Sync  50  authenticates the ID code to determine that GT-TOF camera  31  is indeed a GT-TOF camera subscribed to CAM-Sync  50 . If authenticated, CAM-Sync  50  transmits a sign-in acknowledgement message to GT-TOF camera  31  confirming sign-in. In an embodiment, GT-TOF camera  31  is also configured to initiate, substantially upon being turned on, or alternatively, after turn-on, upon receiving a sign-in acknowledgment message from CAM-Sync  50 , a radio scan to detect radio broadcasts that indicate that there are other subscriber GT-TOF cameras in an imaging neighborhood of GT-TOF camera  31  that might interfere with operation of GT-TOF camera  31 . In  FIG. 1A , an imaging neighborhood of GT-TOF camera  31  is schematically indicated by a dashed ellipse  40 , and GT-TOF camera  31  is an only GT-TOF camera subscribed to CAM-Sync  50  in the imaging neighborhood. As a result, GT-TOF camera  31  fails to detect any broadcasts that might indicate presence of another subscriber GT-TOF camera in imaging neighborhood  40 . 
         [0019]    In an embodiment, failing to detect radio broadcasts indicating presence of another subscriber GT-TOF camera in imaging neighborhood  40 , GT-TOF camera  31  communicates with CAM-Sync  50  to request that CAM-Sync  50  optionally provide GT-TOF camera  31  with a service set identifier (SSID) for establishing a WLAN and an associated access code that other subscriber GT-TOF cameras may present to GT-TOF camera  31  to be granted access to the WLAN. In response, having authenticated identity of GT-TOF camera  31  as noted above, CAM-Sync  50  transmits a message to GT-TOF camera  31  providing the GT-TOF camera with an SSID and an associated access code. A double arrowhead dashed line  41  schematically represents communication between GT-TOF camera  31  and CAM-Sync  50 . Line  41  is labeled with the information that may be communicated between the GT-TOF camera and CAM-Sync  50 . 
         [0020]    Upon receiving the SSID and associated access code, GT-TOF camera  31  broadcasts a beacon comprising the SSID to disclose presence of GT-TOF camera  31  and availability of a WLAN identified by the SSID. Cascaded arcs  33  schematically represent the beacon transmitted by GT-TOF camera  31 . Optionally, in the message that CAM-Sync  50  transmits to GT-TOF camera  31  to provide the camera with the SSID and access code, CAM-Sync  50  provides GT-TOF camera  31  with a transmission signal strength at which to transmit beacon  33 . In an embodiment, CAM-Sync  50  determines the transmission signal strength to limit a broadcast range for which beacon  33  may effectively be detected and recognized by other subscriber GT-TOF cameras. The transmission signal strength and resulting broadcast range of the beacon may be determined to define an extent of imaging neighborhood  40 . Optionally, in the acknowledgment message transmitted to GT-TOF camera  31  CAM-Sync  50  provides GT-TOF camera  31  with a radiant power level at which to transmit light pulses that the GT-TOF camera transmits to illuminate lion  29  and acquire a range image of the lion. In an embodiment CAM-Sync  50  determines the broadcast range of beacon  33  based on the radiant power level at which GT-TOF camera  31  operates so that beyond the beacon broadcast range, light pulses transmitted by GT-TOF camera  31  do not substantially interfere with operation of other, similar GT-TOF cameras. As long as no other subscriber GT-TOF camera operates within imaging neighborhood  40 , GT-TOF camera  31  images lion  29  without time constraints. 
         [0021]      FIG. 1B  schematically shows imaging neighborhood  40  after a visitor  22  to the zoo has brought a second GT-TOF camera  32  subscribed to CAM-Sync  50  to imaging neighborhood  40  and turned on the camera to range image lion  29 . Optionally, upon being turned on in imaging neighborhood  40 , GT-TOF camera  32  transmits the same type of data to CAM-Sync  50  that GT-TOF camera  31  transmitted to the CAM-Sync when GT-TOF camera  31  was turned on. Upon receiving the data transmitted by GT-TOF camera  32  CAM-Sync  50  may transmit an acknowledgement message to GT-TOF camera  32  comprising a threshold reception signal strength for detecting a beacon transmitted by another subscriber GT-TOF camera, such as GT-TOF camera  31 . In an embodiment, having been notified of the presence of GT-TOF camera  32  in imaging neighborhood at the lion enclave, and assigning GT-TOF camera  31  a transmission signal strength for transmitting beacon  33 , CAM-Sync  50  sets the reception signal strength assigned to GT-TOF camera  32  responsive to the transmission signal strength of beacon  33  to determine an extent of imaging neighborhood  40 . 
         [0022]    Upon receiving the acknowledgement message from CAM-Sync  50 , GT-TOF camera  32  initiates scanning for radio transmissions from other subscriber GT-TOF cameras. However, unlike the scan performed by GT-TOF camera  31  discussed above, the radio scan performed by GT-TOF camera  32  results in GT-TOF camera  32  detecting a beacon transmitted by another subscriber GT-TOF camera in neighborhood  40 —beacon  33  transmitted by GT-TOF camera  31 . Upon detecting beacon  33  transmitted by GT-TOF camera  31 , GT-TOF camera  32  processes the beacon to determine the SSID the beacon encodes, and transmits a message that informs CAM-Sync  50  that GT-TOF camera  32  has detected beacon  33  encoding the SSID and requests the access code associated with the SSID so that GT-TOF camera  32  can join the WLAN identified by the SSID. In  FIG. 1B  a double arrowhead dashed line  42  represents communication between GT-TOF camera  32  and CAM-Sync  50 . Upon receiving the access code, GT-TOF camera  32  transmits a “request message” to GT-TOF camera  31  encoding the ID of GT-TOF camera  32  requesting access to the WLAN and presenting the access code. A cascade of arcs  34  represents the message that GT-TOF camera  32  transmits to GT-TOF camera  31  requesting access to the WLAN. 
         [0023]    Upon receiving the ID and access code from GT-TOF camera  32 , GT-TOF camera  31  allows GT-TOF camera  32  access to the WLAN and transmits messages to GT-TOF camera  32  over the WLAN that instructs GT-TOF camera  32  to operate as a “slave” in a TDM imaging mode administered by GT-TOF camera  31  operating as a “master” of the WLAN. Operating as a master, GT-TOF camera  31  allocates imaging time slots to time division multiplex operation of both GT-TOF cameras  31  and  32  so that the GT-TOF cameras range image lion  29  at different times. Master GT-TOF camera  31  acquires range images only during imaging time slots that the master GT-TOF camera allocates to itself, and slave GT-TOF camera  32  acquires range images only during imaging time slots that master GT-TOF camera  31  allocates to slave GT-TOF camera  32 . 
         [0024]    In an embodiment, master GT-TOF camera  31  alerts slave GT-TOF camera  32  to an onset of an allocated imaging time slot by transmitting over the WLAN an image-ON signal. An image-ON signal may encode the ID of slave GT-TOF camera  32 , a start time of an imaging time slot allocated to the slave GT-TOF camera and a duration of the imaging time slot. The duration of an imaging slot that master GT-TOF camera  31  allocates to slave GT-TOF camera  32  and/or frequency with which master GT-TOF camera  31  allocates imaging time slots to slave GT-TOF camera  32  may be customized to the slave camera&#39;s operating profile. Master GT-TOF camera  31  may be informed of slave GT-TOF camera&#39;s operating profile by messages that the slave camera transmits or by profile data that CAM-Sync  50  stores in database  51  for GT-TOF camera  31  and makes available to GT-TOF camera  31 . For example, the imaging time slot duration may be longer or shorter depending on intensity of illumination slave GT-TOF camera  32  is able to provide to illuminate lion  29  to range image the lion. Slave GT-TOF camera  32  may transmit status messages to master GT-TOF camera  31 , and/or CAM-Sync  50 , comprising “status parameters” indicating how ready slave GT-TOF camera  32  is to use an allocated imaging time lot, or how frequently the slave camera is able to use imaging time slots. The status message may for example, contain data indicating camera temperature, and/or power reserves. Master GT-TOF camera  31  may determine when and/or frequency with which it provides slave GT-TOF camera  32  with imaging time slots responsive to the parameters in the status message. Slave GT-TOF camera  32  optionally transmits a “receipt message” to master GT-TOF camera  31  to acknowledge receipt of an image-On signal that it receives from the master GT-TOF camera. 
         [0025]    Additional subscriber GT-TOF cameras that enter imaging neighborhood  40  may communicate with CAM-Sync  50  and GT-TOF camera  31  similarly to the manner in which GT-TOF camera  32  communicated with CAM-Sync  50  and GT-TOF camera  31  to access and become a member of the WLAN, and operate as a slave in the TDM imaging mode administered by master GT-TOF camera  31 . In an embodiment, each member GT-TOF camera of the WLAN established to support the TDM imaging mode for GT-TOF cameras located in imaging neighborhood  40  may periodically broadcast the SSID of the WLAN to alert non-member GT-TOF cameras to the existence of imaging neighborhood  40  and the neighborhood&#39;s TDM imaging mode that the WLAN supports. Alerted non-members may communicate with CAM-Sync  50  to acquire the access code needed for joining the WLAN and participating in the TDM imaging mode administered for imaging neighborhood  40 . Having all members of the WLAN broadcasting the WLAN SSID enables non-member GT-TOF cameras that are too far from master GT-TOF camera  31  to effectively detect beacons that the master camera transmits, to join the WLAN, and enables imaging neighborhood  40  to grow as might be needed substantially independent of a range of beacons transmitted by any of the GT-TOF cameras that are members of the WLAN. 
         [0026]    A slave GT-TOF camera may exit the TDM imaging mode by transmitting an “exit message” to master GT-TOF camera  31 , or by not responding with a receipt message in response to an image-ON signal it receives from the master GT-TOF camera. Master GT-TOF camera  31  may relinquish the role as master by transmitting a “master exit” message to a slave GT-TOF camera appointing the slave GT-TOF as a new master to administer the WLAN and TDM operation of remaining GT-TOF slave cameras active in neighborhood  40 . 
         [0027]    It is noted that the physical extent of imaging neighborhood  40  is not static and may grow or shrink as GT-TOF cameras subscribed to CAM-Sync  50  enter or leave the imaging neighborhood. A GT-TOF camera, such as GT-TOF camera  31  or  32  may enter an imaging neighborhood by physically entering the neighborhood while on, or by being turned on while in the neighborhood. A GT-TOF camera, may exit an imaging neighborhood by physically leaving the neighborhood while on, or by being turned off. 
         [0028]    In an embodiment of the disclosure CAM-Sync  50  may implement a TDM imaging mode for a plurality of subscriber GT-TOF cameras by directly allocating imaging time slots to the GT-TOF cameras.  FIG. 2  schematically illustrates CAM-Sync  50  directly administering a TDM imaging mode for a plurality of, by way of example five, GT-TOF cameras  131 ,  132 , . . . ,  135  located in imaging neighborhood  40 . 
         [0029]    In an embodiment each GT-TOF camera  131 , . . . ,  135  subscribed to CAM-Sync  50  is configured by a CAM-Sync app it comprises to repeatedly communicate to CAM-Sync  50  when the GT-TOF camera is turned on to be used to acquire a range image, the ID of the GT-TOF camera and data that may be used to determine a geolocation of the GT-TOF camera. CAM-Sync  50  may processes the ID and geolocation data to determine when two or more GT-TOF cameras subscribed to CAM-Sync  50  become close enough to create an imaging neighborhood in which the cameras may interfere with each other&#39;s operation. When such a situation comes about, as schematically shown in  FIG. 2  for the lion enclave and GT-TOF cameras  131 , . . . ,  135 , CAM-Sync  50  transmits a TDM control signal to each GT-TOF camera that prevents the GT-TOF camera from operating, and by way of example, transmitting light to illuminate and range image lion  29  unless the GT-TOF camera receives an image-ON signal from CAM-Sync  50 . 
         [0030]    As for the case of establishing a WLAN that enables GT-TOF cameras to communicate on a peer to peer basis and cooperate in administering a TDM imaging mode, discussed above with respect to  FIGS. 1A and 1B , each image-ON signal that CAM-Sync  50  transmits may encode the ID of a GT-TOF camera  131 , . . . ,  135  to address the image-ON signal to its intended destination GT-TOF camera, a start time of an imaging time slot allocated to the GT-TOF camera, and a duration of the imaging time slot. The duration of an imaging slot allocated to a destination GT-TOF camera  131 , . . . ,  135  and/or frequency with which CAM-Sync  50  allocates imaging time slots to the destination camera may be customized to the camera&#39;s operating profile. For example, the imaging time slot duration may be longer or shorter depending on intensity of illumination that the GT-TOF camera is able to provide to illuminate lion  29  to range image the lion. And, in an embodiment, each GT-TOF camera  131 , . . . ,  135  may transmit a status message to CAM-Sync  50  that provides CAM-Sync  50  with status parameters indicating availability of the camera for using an allocated imaging time lot, or how frequently the camera is able to use imaging time slots. CAM-Sync  50  may determine when and/or frequency with which it provides the GT-TOF camera with imaging time slots responsive to the parameters in the status message. 
         [0031]    It is noted, that whereas in the above discussion a CAM-Sync and TDM imaging modes are described with respect to active illumination GT-TOF cameras CAM-Syncs and TDM operating modes in accordance with embodiments of the disclosure are applicable to managing operations of any types of cameras that might interfere with each other&#39;s operations when operating in a same venue. For example a CAM-Sync may establish, and/or manage TDM operating modes in accordance with an embodiment of the disclosure for structured light cameras, strobe cameras, and/or flash cameras. 
         [0032]    In the description and claims of the present application, each of the verbs, “comprise” “include” and “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of components, elements or parts of the subject or subjects of the verb. 
         [0033]    Descriptions of the various embodiments in the present application are provided by way of example and are not intended to limit the scope of the claimed subject matter. The described embodiments comprise different features, not all of which are required in all embodiments of the subject matter. Some embodiments utilize only some of the features or possible combinations of the features. Variations of embodiments that are described, and embodiments comprising different combinations of features noted in the described embodiments, will occur to users of the art. The scope of the embodiments is defined by the claims.
Apparatus for controlling a plurality of active illumination cameras to operate in a time division multiplexed operating mode to acquire images of scenes that the cameras image.