Abstract:
The present invention relates to an automated camera control system ( 10 ). The automated camera control system ( 10 ) is a control management system for television broadcasting at a track based event, such as horse or motor racing. The automated camera control system ( 10 ) allows a single operator ( 54 ) to simultaneously control a plurality of cameras ( 16 ). The automated camera control system ( 10 ) improves the compositional quality of the footage. The operator ( 54 ) can simultaneously perform all the functions of a director including vision switching and camera setting for the outgoing television broadcast ( 86 ).

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a national stage of PCT/AU2005/001302 filed Aug. 30, 2005, under the International Convention. 
     FIELD OF THE INVENTION 
     The present invention relates to a camera control system. 
     BACKGROUND OF THE INVENTION 
     Sporting events have become popular with television audiences as the program provides superior coverage of the event. This is particularly true in sporting events such as motor racing where a spectator at the event is only able to glimpse a small part of the action. Television networks utilise a plurality of cameras at such events in an attempt to provide the best coverage for viewers, including car mounted, aerial, and tripod mounted and mobile cameras. 
     Typically a human operator is required to manually operate each camera. 
     Usually, these cameras are deliberately placed at particular locations around a race course in order to capture the best footage of the race. One of the difficulties with currently available systems is that the human operator may both miss action and incorrectly operate the camera. Furthermore, the cost associated with having to employ human operators for most cameras is financially restrictive. 
     Another use for cameras at sporting events is to capture images of the sporting contest for later viewing. This is particularly important in such sporting events as horse racing when protests are lodged after the race for reasons such as interference. In horse racing stewards study video replays from vantage points around the course to gauge if interference between the race participants has occurred. For this reason cameras referred to as “stewards cameras” are placed at particular locations around the race course to capture footage of the sporting event. 
     Sporting events such as thoroughbred, harness, greyhound and motor racing all have highly repetitive and formula driven broadcasts, which have simple requirements for the camera operator&#39;s framing. In the case of thoroughbred racing there are multiple camera operators employed although they are used only a fraction of the time while they are on site. 
     It is an object of the present invention to provide for a method and apparatus of camera control that overcomes at least some of the aforementioned problems or provides the public with a useful alternative. It is yet a further object of the present invention to provide for a method and apparatus of camera control that provides a labour saving solution. 
     It is still yet a further object of the present invention to provide for a method and apparatus of camera control that enhances accuracy and quality of the captured image. 
     SUMMARY OF THE INVENTION 
     Therefore in one form of the invention there is proposed an apparatus for camera control including: a plurality of slaved cameras each controllably adapted to assume a plurality of viewing directions; a control apparatus in communication with the plurality of slaved cameras and adapted to control the direction of the plurality of slaved cameras to simultaneously track a spatial node, moving at a known velocity and in a known direction. 
     Preferably, the node moves along a predetermined spatial path. 
     Preferably, the node can be offset from the predetermined spatial path in the horizontal and vertical planes. 
     Preferably, the apparatus individually controls separate functions of each of the slaved cameras. 
     Preferably, the functions are pan, tilt, zoom and focus. 
     Preferably, the functions are pre-programmed. 
     Preferably, the plurality of slaved cameras can be adapted to sequentially track one or more nodes. 
     Preferably, the plurality of slaved cameras are configured to frame a specified field of view around the node of known zoom length and zoom width. 
     Preferably, the field of view of the slaved cameras is manually adjusted. 
     Preferably, the field of view of the slaved cameras is automatically adjusted. Preferably, the field of view of the slaved camera encompasses an area surrounding the node regardless of the geographical location of the node. 
     Preferably, the zoom length can be controlled. 
     Preferably, the zoom width can be controlled. 
     Preferably, the field of view of each of the slaved cameras is collectively controlled by a zoom trigger device. 
     Preferably, the field of view of any one slaved camera is individually controlled using an individual zoom slider. 
     Preferably, the field of view of all slaved camera is controlled using a joystick zoom trigger and zoom thumb toggle. 
     Preferably, the size of the area surrounding the node is pre-programmed. 
     Preferably, the plurality of slaved camera&#39;s field of view around the node can be individually proportionally enlarged and contracted from the default field of view around the node using individual zoom sliders. 
     Preferably, the slaved cameras are adapted to automatically focus on the node. 
     Preferably, the velocity of the node is manually controlled. 
     Preferably, the velocity of the node is preprogrammed. 
     Preferably, the velocity of the node can be replayed after a manually altered preprogrammed run. 
     Preferably, apparatus for camera control further includes at least one unslaved camera. 
     Preferably, the slaved and unslaved cameras are mounted on an encoded servo pan tilt head apparatus. 
     Preferably, the node is sent to a known start position. 
     Preferably, the direction of movement of the node can be changed. 
     Preferably, the node is configured to assimilate with a desired target. 
     Preferably, the apparatus can recognise and interact with multiple nodes. 
     Preferably, the slaved and unslaved cameras are controlled using a joystick. 
     Preferably, the predetermined path includes a plurality of milestones. 
     Preferably, the velocity of the node and the slaved camera&#39;s focus, pan, tilt, and zoom functions are preprogrammed to specific milestones. 
     In a further form of the invention there is proposed a method of camera control including the steps of:
     surveying a sporting environment;   placing a plurality of slaved cameras within the sporting environment;   determining the location of each individual camera;   controlling the movement of the plurality of slaved cameras, via a control apparatus, to simultaneously track a spatial node, moving at a known velocity and in a known direction.   

     Preferably, the plurality of cameras includes slaved and unslaved cameras. 
     Preferably, a camera&#39;s location is determined by the use of a plurality of survey markers and a resection survey method. 
     Preferably, one or more cameras are aligned onto the node. 
     Preferably, the slaved and unslaved cameras are mounted on an encoded servo pan tilt head to facilitate the tracking of the node. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings, 
         FIG. 1  is a schematic view of a first embodiment of a camera control system embodying the present invention; 
         FIG. 2  is a schematic view of a track including a predetermined path and node illustrating x, y, z axes; 
         FIG. 3  is a top view of a horse racing track including a predetermined path and node; 
         FIG. 4  is a schematic view of the camera control system of  FIG. 1  illustrating control of the forward movement of the node; 
         FIG. 5  is a schematic view of the camera control system of  FIG. 1  illustrating control of the sideways lateral movement of the node; 
         FIG. 6  is a second embodiment of the camera control system illustrating its use in relation to a horse race; 
         FIG. 7  is a top view of the interface panel of the camera control system of  FIG. 6 ; 
         FIG. 8  is a schematic view of a zoom window; 
         FIG. 9  is a schematic view of the camera control system of  FIG. 1  illustrating slaved and unslaved cameras; 
         FIG. 10  is a top view of the horse racing track of  FIG. 3  illustrating milestones; and 
         FIG. 11  is a schematic view of a third embodiment of the camera control system illustrating a motor race circuit including an electronic eye. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same and like parts. Referring to the drawings for a more detailed description, a camera control system  10  is illustrated in  FIG. 1 , demonstrating by way of example one arrangement in which the principles of the present invention may be employed. The camera control system  10  includes a control apparatus  12  which is in communication  14  with a plurality of cameras  16 . The control apparatus  12  is configured to control the movement of the cameras  16  to simultaneously train their respective centre lines  18  on a node  20  while automatically adjusting the field of view  70  ( FIG. 7 ) and focus requirements. In this way a single operator can control a plurality of cameras  16  thereby avoiding the requirement of having an individual camera operator for each individual camera  16 . The node  20  tracks along a predetermined path  22  within known parameters such as a race course  24 . The camera control system  10  further includes control software (not shown) which controls predetermined functions of the invention. In its simplest form the operator can simply move the node  20 . 
     The predetermined path  22  is established through a survey of a particular track  24 . The surface of the track  24  is mapped and a mathematical matrix is calculated. A node  20  is then placed on a predetermined path  22  that typically follows the centre of the track in horse racing and the racing line in motor sports. Accordingly the node  20  has a series of predetermined x, y, z coordinates that are stored in a data table. The data table produced from the survey of the track  24  is stored for future use. The location of each of the individual cameras  16  is either determined by a survey or by a method commonly used by surveyors and referred to as a ‘resection’. A ‘resection’ involves aligning and focusing the centre line  18  of each of the randomly located cameras  16  consecutively on a series of survey markers (not shown) with known geographical locations around the track  24 . The survey markers are typically 600 mm circular signs with a painted crosshair. As the camera&#39;s  16  centre line  18  is aligned with three or more survey marker the camera&#39;s  16  orientation, namely its pan and tilt, is logged thereby enabling the geographical location of the camera  16  to be calculated. Alternatively, each camera  16  can include a GPS device which automatically calculates the position of the camera  16  and the camera need only be aligned to one survey marker. The geographical position and the pan and tilt information is then transmitted to the control apparatus  12 . As the reader would appreciate the camera control system  10  can be used at any race track. The different tracks are surveyed to collect the geographical position of inside and outside rails, start area, finish line and installed survey markers which are used to resection the cameras  16 . The survey information is entered into a software program such as CAD and milestones are inserted. The x, y, z coordinates of the predetermined path  22  are then entered into a data matrix and a mathematical model is produced that plots the movement of a node  20  at a preset velocity. A data matrix is also used to calibrate the field of view  70  of the plurality of cameras  16  such that the centre line  18  tracks the node  20  as it travels along the predetermined path  22 . 
     As further illustrated in  FIG. 1 , the control apparatus  12  includes an interface panel  26  which is connected by way of cable  28  to a network device  30 . The network device  30  communicates  14  with each of the cameras  16 . It is envisaged that the communication  14  will be in the form of a broadcast signal. However, the communication could be by way of fixed cables where existing race infrastructure is used such as Steward&#39;s or viewing towers at horse racing events. The interface panel  26  includes, but is not limited to, a node velocity control bar  32 , a joystick  34 , a series of camera specific controls  36  and auxiliary switches  38 . The interface panel  26  enables an operator to either independently control the pan, tilt and zoom of each of the cameras  16  or simultaneously control the movement of selected cameras  16  to track the movement of the node  20 . Pan is defined as the side-to-side camera movement, the tilt is the up-and-down camera movement and the zoom is the visual in-and-out camera movement. The operator  54  either manually controls the camera&#39;s  16  focus or alternatively, the focus is automatically calculated as is well known in the prior art. The auto focus function is able to be calculated by the camera control system  10  because the positions of the cameras  16  and the position of the node  20  are known, there by enable the lens&#39;s focal distance to calculated for a specified lens. It is envisaged that the cameras  16  will be mounted on encoded pan tilt servo heads or similar apparatus. Encoded pan tilt servo heads are able to calculate their pan and tilt bearings at all times. 
     As illustrated in  FIG. 2 , the node  20  has a known spatial position along x, y, z coordinates  40 ,  42  and  44 . In use the node  20  is used to track the position of race participants, for instance horses or greyhounds on a race track or a vehicle on a race course. Typically, when used in horse racing the node  20  is placed by the operator  54  in the centre of a group of race participants. 
     The node  20  can be set at any height above or below the predetermined path  22 . This lateral displacement of the node  20  along the z axis  44  is manually adjusted via the control apparatus  12  or can be preset. It is envisaged that the camera control system  10  will include a data table that stipulates any predetermined displacement. Similarly, the centre line  18  of the camera  16  can be displaced from the node  20  in the vertical and horizontal planes during operation via the control apparatus  12 . 
     The node  20  has a predetermined starting point  46  along the predetermined path  22 . As illustrated in  FIG. 3 , the predetermined path  22  may correspond to a horse racing track with starting stalls  48  and a finishing line  50 . The node  20  begins at the starting point  46  and moves in the direction of arrow  52  to the finishing line. It should be appreciated that each horse racing track may have several predetermined paths  22  as there can be several starting points around each race course. In practice it would simply be a matter of the operator selecting the appropriate starting point and corresponding predetermined paths  22 . 
     As illustrated in  FIG. 4 , the operator  54  is able to control the forward movement of the node  20  along the predetermined path  22  by way of the node velocity control bar  32 . The node velocity control bar  32  can be configured to particular velocity and acceleration calibrations and acts in a similar way to a thrust lever of a commercial airplane. As the operator moves the node velocity control bar  32  in the direction of the arrow  56  the velocity of the node  20  increases. Movement of the node velocity control bar  32  in the opposite direction would slow the speed of the node  20 . 
     The velocity of the node  20  is controlled in typically three different ways. 
     Firstly, the speed of the node  20  can be directly controlled by the velocity control bar  32 . A calibrated forward movement of the node velocity control bar  32  in the direction of the arrow  56  corresponds to an increase in the velocity of the node  20 . A calibrated movement of the node velocity control bar  32  in the opposite direction results in a corresponding decreased velocity of the node  20 . 
     Secondly, a particular speed can be specified to control the movement of node  20 . The camera control system  10  can include a means of setting a predetermined velocity of the node  20 . It is envisaged that the camera control system  10  will include a data table that enables the operator  54  to specify the speed of the node  20  within a variety of distances on a predetermined path  22 . This specified speed still enables the operator  54  to make minor adjustments to the velocity of the node  20  using the node velocity control bar  32 . This would be relevant where the speed of the race participants can be accurately estimated, for instance the speed of a vehicle around a race circuit or horse on a race track. 
     Third and finally, a delta speed function can be used to control the velocity of the node  20 . The delta speed function is a derivative of the preset speed function wherein the node  20  moves at a predetermined velocity plus or minus the last manual adjustments of the node velocity control bar  32  performed by the operator. 
     The node  20  can be displaced from the predetermined path  22  in the vertical and horizontal planes. This displacement may be to take account of advertising that is displayed on television screens or to visually frame the race participants. As illustrated in  FIG. 5 , the lateral displacement of the node  20  from the predetermined path  22  is controlled by way of the joystick  34 . When the joystick  34  is moved in the direction of arrow  58  the node  20  is displaced to the right of the predetermined path  22 , or towards the outside rail, as indicated by arrow  64 . Accordingly the centre line  18  of the camera  16  also moves to the right of the predetermined path  22 . When the joystick  34  is moved in the direction of arrow  62  the node  20  and therefore the centre line  18  of the camera  16  moves to the left of the predetermined path  22  as indicated by arrow  60 . 
     To assist in explaining the principles of the present invention the camera control system  10  will be described as being used to capture footage at a horse racing event. In a preferred embodiment, as illustrated in  FIG. 6 , the camera control system  10  is used to capture footage of a group of race participants, in this example being a group of horses  66 . The node  20  is placed in the centre of the group of horses  66  and framed within zoom window  68 , which is determined by the zoom width and length. The centre line  18  of the field of view  70  of each camera  16  tracks the node  20 . The control apparatus  12  is in communication  14  with each of the cameras  16  via the network device  30 . As illustrated in  FIG. 6 , each camera  16  includes a communication device  72  and is mounted on an encoded servo pan tilt head and tripod apparatus  74 . The camera control system  10  further includes auxiliary cameras  76  with corresponding communication devices  78 . These auxiliary cameras  76  can be placed at different locations around the track  24  to capture crowd shots or landscape footage. These auxiliary cameras  76  are controlled by the operator  54  and may be configured to track the node  20 . 
     Unslaved cameras  16   b  or locked off cameras are utilised by the joystick operated switch  92  which enables their pan tilt zoom and focus to be set using the joystick  34 , joystick zoom trigger and the focus wheel  102 . When the joystick operator switch  92  is on, then the joystick  34 , focus wheel  102  and joystick zoom trigger only control that specific camera  16 . Switching off the joystick operated switch  92  sets the unslaved cameras  16   b  in that position and resets the joystick  34  to control the slaved cameras  16   a . The zoom sliders  88  may still be utilised for individual slaved  16   a  and unslaved  16   b  cameras at all times. 
     Each of the cameras  16  and  76  transmits a signal  80  which is received by the control apparatus  12 . The footage captured by each particular camera  16  and  76  is displayed on a separate display screen  82 . The operator  54  is then able to select the best footage for the television production which is displayed on a master display  84 . The television production is then broadcast  86  using a conventional analogue or digital signal. 
     As illustrated in  FIG. 7 , the interface panel  26  includes a node velocity control bar  32 , a joystick  34 , a series of camera specific controls  36  and auxiliary switches  38 . The camera specific controls  36  include a zoom slider  88 , a slave switch  90  and a joystick operation switch  92 . The slave switch  90  aligns the centre line  18  of the camera  16  with the node  20 . The slave switch  90  engages the functions of the camera data table software and enables the selected camera&#39;s pan, tilt, zoom and focus calibrations to be automatically adjusted. The joystick operation switch  92  overrides the slave switch  90  and enables the operator  54  to independently control the pan, tilt and zoom of a specific camera  16  or  76 . 
     The joystick  34  serves several functions; firstly it is able to control the cameras  16  or  76  which have the joystick operated switch  92  engaged. This enables the operator  54  to control the tilt, pan and zoom of individual cameras. Secondly, the joystick  34  is adapted to control the lateral displacement of the node  20  from the predetermined path  22 . Thirdly, the joystick  34  is used to control the length and width of the zoom window  68 . 
     The auxiliary switches  38  control programmed commands of the control software and enables the programming of a variety of visual sequences. The camera programming takes into consideration: multiple cameras, node  20  positions, pan calibrations, node  20  speed, zoom calibrations, timing functions, slaving and unslaving cameras and focus. An example of this visual sequencing of cameras is the finish of a horse race whereby the operator  54  presses a designated function button which allows a designated camera to follow the node  20  until it reaches a specified pan point, namely the finish line  50 , at which point the camera unslaves from the node  20  and frames the finish line  50  in a specified zoom and pan calibration. Once all the horses have passed the finish line  50 , the function button is engaged and the designated camera pans and zooms in a specified manner until it catches up to the node  20  which at this point has been slowed down by the operator  54  and is located directly adjacent to the winner. These visual sequences enable simple pre-composed choreographed cinematic sequences to be executed by one operator in real time using one or more cameras  16  and  76 . 
     The interface panel  26  includes a preset speed switch  94  and direction change switch  96  associated with the node velocity control bar  32 . The interface panel  26  also includes a coloured LED display  98  which corresponds with the position of the node velocity control bar  32 . The delta speed switch  100  controls the operation of the delta speed function as previously discussed. While the focus wheel  102  is used to focus cameras  16  or  76  which have the joystick operated switch  92  engaged. The interface panel  26  further includes broadcast director operation controls, namely preview switches  104 , final broadcast switches  106  and director fade bar  108  as is well known in the art. 
     As further illustrated in  FIGS. 8 and 9 , the zoom window  68  is determined by the zoom width  110  and zoom length  112 . These zoom parameters can be automatically set by the control software or adjusted in real time by the operator  54  via the joystick zoom trigger. In the present example the node  20  is located in the centre of the zoom window  68 , however it should be appreciated that the node  20  could be dynamically located at a plurality of points within the zoom window  68  depending on the shot required. It is envisaged that the joystick will include a zoom trigger (not shown) which controls the length  112  of the zoom window  68  and a thumb toggle (not shown) which controls the width  110  of the zoom window  68 . 
     The zoom window  68  enables all slaved cameras  16   a  to frame the same volume of space regardless of the camera&#39;s  16   a  position and angle. This is particularly useful for horse and dog racing where all entrants need to be framed in shot by multiple cameras around the track  24 . The zoom window  68  is a volume of space defined by a zoom length  110  &amp; zoom width  112 . The node  20  is typically at the centre of the zoom window  68 . This known zoom window  68  enables all slaved cameras  16   a  at all locations to zoom in and frame only the desired zoom window  68  in the camera&#39;s  16   a  field of view  70 . Slaving a camera  16   a  also automatically focuses the camera  16   a  onto the node  20 , the distance between the camera  16   a  and node  20  is the focal length that the camera control system  10  uses to calculate the required focus calibration dependent on the camera  16   a  lens specified in the camera control system&#39;s  10  software. 
     The zoom length  110  and zoom width  112  are controlled by the joystick  34 . 
     The node  20  is at the centre of the zoom window  68 , and as such the zoom window  68  can be moved in the same manner as the node  20  is moved. The individual zoom slider  88  for each camera  16  allows the operator  54  to expand or contract a camera&#39;s field of view  70  even if the camera  16   a  is slaved. In the case of a slaved camera  16   a  with a zoom slider  88  set at 20% then the default zoom window  68  size would be enlarged by 20%. If all slaved camera&#39;s  16   a  zoom sliders  88  are set at zero then the zoom window  68  is an identical space. 
     When a camera  16  is locked off or not in slaved mode then the zoom slider  88  still controls the camera  16  zoom calibrations. When a camera  16   b  has been switched to joystick operated  92  mode then the joystick  34  and in particular the joystick trigger (not shown) controls the camera&#39;s  16   b  zoom function. 
       FIG. 9  further illustrates the use of a slaved camera  16   a  and an unslaved camera  16   b . The slave switch  90  that corresponds to the camera  16   a  is engaged. 
     Accordingly, camera  16   a  tracks node  20  as previously discussed. In contrast when the joystick operated switch  92  that corresponds to the camera  16   b  is engaged the operator  54  is able to independently position the camera  16   b  by use of the joystick  34 . For instance, the unslaved camera  16   b  can be focused  70  on the grandstand  114  for a crowd shot. 
     The camera control system  10  may include a random start function. The camera control system  10  recognises the location of the track  24  and where a camera  16  and its encoded pan and tilt head is pointing. The operator  54  can aim the camera  16  at any location on the track  24  and activate the random start function which will automatically focus the camera  16  and follow a node  20  inserted at that random point at a specified preset speed. The random start node  20  travel path will be initially parallel to the predetermined path  22  but will be dragged onto the predetermined path  22  in prescribed manner as specified by control software. Each track  24  will have a defined coordinate map or drawing showing where the node  20  can travel parallel to the predetermined path  22  and where the node  20  will be automatically dragged onto the predetermined path  22 . Manual adjustments to the node  20  may still occur in real time. 
     In an alternate embodiment the camera control system  10 , as illustrated in  FIG. 10 , utilises a series of milestones  116 ,  118 ,  120 ,  122  and  124  which are surveyed locations around a track  24  at uniform distances i.e. 10 m or 100 m. These milestones  116 ,  118 ,  120 ,  122  and  124  are used in conjunction with programmed commands which can be loaded onto the auxiliary switches  38 . The milestones within the programmed commands enables the operator  54  to set the configuration of individual cameras  16  including their zoom, focus, pan, tilt, slaved, unslaved, node speed and node offset from the predetermined path at these points. These milestones  116 ,  118 ,  120 ,  122  and  124  enable a choreographed sequence of footage to be attached to a geographical location. 
     In a further alternate embodiment the camera control system  10 , as illustrated in  FIG. 11 , is used in conjunction with an electronic eye  126  to track a motor car  128 . The camera control system  10  can manage multiple nodes  20  which can be generated via an electronic eye  126  or manually. These multiple nodes  20  are initially inserted on the predetermined path  22  at the prescribed speed but can be manually adjusted. The operator  54  can skip from one node  20  to the next, either up or down the race order via the interface panel  26 . The camera control system  10  also has a home function where the camera  16  is taken back to a specified direction until the next node  20  passes by. Continuously pressing the home function button will enable nodes  20  to pass without the camera  16  being slaved to the node  20 . Typically the electronic eye  126  is used to initiate the movement of the node  20 , whereby when the electronic eye is broken the node  20  begins to move along the predetermined path  22  at a predetermined velocity. 
     Although the cameras  16  are described as being rotatably fixed to a particular geographical location, it should be appreciated by the reader that the present invention is not limited to this configuration. The present invention could be used on mobile cameras such as those mounted on tracks providing the geographical position of the camera was known. For instance, this could be accomplished by attaching a GPS unit to the camera and having a real time feed to the controller. In this way the geographical position of the camera  16 , in relation to node  20 , would be known at all times. 
     The skilled addressee will now appreciate the many advantages of the present invention which provides for a camera control system. The camera control system can be used on different race courses and under different conditions. The use of slaved cameras provides cost benefits as separate operators are not required for each camera. The system also provides flexibility to provide the best coverage of course based sporting events. The precision gained from a slaved camera to a node also significantly increases the quality of broadcast footage and enables new and innovative approaches to broadcasting of sporting events. 
     It should be appreciated that the camera functions of zoom, tilt and pan have not been explained within the specification as they would be obvious to the person skilled in the art. The reader should understand that the invention resides in the use of a plurality of slaved camera that are configured to track a spatial node along a predetermined path. 
     Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention. 
     In any of the claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprising” is used in the sense of “including”, i.e. the features specified may be associated with further features in various embodiments of the invention.