AU2007237231B2

AU2007237231B2 - Player Position Validation Interface

Info

Publication number: AU2007237231B2
Application number: AU2007237231A
Authority: AU
Inventors: Michael Hagedorn; Kenji Irie
Original assignee: Lincoln Ventures Ltd
Current assignee: Lincoln Ventures Ltd
Priority date: 2006-11-30
Filing date: 2007-11-28
Publication date: 2012-02-09
Anticipated expiration: 2027-11-28
Also published as: NZ551762A; ZA200710447B; GB2444407A; GB0723480D0; GB2444407B; AU2007237231A1

Abstract

PLAYER POSITION VALIDATION INTERFACE A method (20) is disclosed of collating a set of valid object positions. The method 5 (20) starts by determining (21) a plurality of candidate object positions. A plurality of validity indicators are then received (26), each validity indicator being associated with a single candidate object position. The set of valid object positions is collated (29) from the candidate object positions using the validity indicators received. Rec Over 1,... Rec Stati * elve Rec, Rec ODe eive Coll ate

Description

P/00/011 28/5/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Lincoln Ventures Limited Actual Inventors Kenji Irie Michael Hagedorn Address for service is: WRAY & ASSOCIATES Level 4, The Quadrant 1 William Street Perth, WA 6000 Attorney code: WR Invention Title: Player Position Validation Interface The following statement is a full description of this invention, including the best method of performing it known to me: 1 PLAYER POSITION VALIDATION INTERFACE TECHNICAL FIELD The present invention relates to a validation interface for an object tracking system. The present invention may be employed to provide such an interface when used in 5 the implementation of an automated player position detection and tracking system.. Preferably the present invention is employed in conjunction with a cricket game to allow an operator of the automated player position detection and tracking system to monitor and correct the output of automated detection and tracking of such a system. BACKGROUND 10 Sports fans enjoy having information which allows them to critique the performance of the team they support, or their teams' opposition. Cricket is a popular bat and ball game in which runs are scored by a batting team playing a fielding team. Cricket is played in an oval shaped field, and generally runs over the course of a few hours, an entire day, or several days. 15 Normally the fielding team is dispersed over the oval playing field, with care needing to be taken with player positioning of the fielding team to ensure batsmen do not hit a ball over the boundary of the field. Player positioning also needs to be carefully considered to return the ball to a bowling player once hit by a batsman to prevent batsmen running between wickets and scoring runs. Small numbers of runs can be 20 scored by running batsmen, whereas four or six runs may be scored if the batsman hits the ball outside the field. Cricket is also a game which has available a large range of standard statistical calculations which can be used to gauge the performance of a team and its players. It would therefore be preferable to have an improved or additional mechanism which 25 can capture data in relation to the positions taken by players during a cricket match. 2 One way of implementing this goal could be through an analysis of video images captured of a cricket game. Computer executable instructions run on a computer system may analyse such video images to detect the positions of players within the images recorded. 5 However, such player detection techniques are not 100% accurate, but their performance generally improves with the addition of numbers of video cameras providing images with different perspectives of a playing field. Furthermore, if the processing algorithms employed are used to batch process the recorded video images after a cricket game, these algorithms may be allowed to run for extended periods of 10 time to improve detection accuracy. However, in some applications the ability to provide such player position data in a timely manner is extremely important. For example, in the case of broadcast television, such data may enable the rendering or display of additional graphics which represent player positions. In the case of cricket games it would be preferable to 15 employ the time present between balls being bowled to broadcast to an audience a live graphics representative of the position and/or movement of players. It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice. Further aspects and advantages of the present invention will become apparent from 20 the ensuing description which is given by way of example only. DIscLOSURE OF INVENTION According to one aspect of the present invention there is provided an automated position detection and tracking system, said method comprising: obtaining real time video images from a single image capture device; 3 executing algorithms for setting initial candidate object position detection and tracking elements; processing said candidate object positions, substantially in real-time; overlaying the initial candidate object positions identified on an image captured 5 previously; allowing an operator to modify the candidate object position detection and tracking elements; allowing an operator to independently add static objects to be graphically presented, and used in tracking candidate object positions; 10 allowing an operator to manually validate or invalidate candidate objects; displaying a graphical representation of validated candidate objects. Preferably the method above further comprises the step of: tracking the movement of at least one object associated with a position within the set of valid object positions. 15 Preferably the method above further comprises the step of: displaying the candidate object positions on a display device, wherein the validity indicators are received from an operator operating a pointing device and associating validity indicators with respective candidate object positions through pointing to the respective candidate object positions and operating a button. 20 The plurality of candidate object positions may be determined from a sequence of video images, and the candidate object positions may be displayed over at least one 4/1 video image of the sequence video images. In one implementation valid validity indicators are received for a set of candidate object positions, and invalid validity indicators are associated with candidate object position excluded from the set of candidate object positions. 5 In another implementation invalid validity indicators are received for a set of candidate object positions, and valid validity indicators are associated with candidate object position excluded from the set of candidate object positions. According to another aspect of the present invention there is provided an apparatus for implementing the above method. 4/2 According to yet another aspect of the present invention there is provided a computer product having stored thereon computer executable instructions for effecting the above method. Other aspects are also disclosed. 5 BRIEF DESCRIPTION OF DRAWINGS Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1 shows a graphical schematic of the components employed by a player 10 position detection and tracking system which employs a player position validation interface according to an embodiment of the present invention; Figure 2 shows a flowchart illustrating computer executable instructions provided to implement the player position validation interface in accordance with 15 a preferred embodiment; Figure 3 illustrates information initially displayed to an operator using the player position validation interface of figure 2 and in particular a number of candidate player positions; Figure 4 illustrates the final output of the player position detection and tracking 20 system implemented using the player position validation interface discussed with respect to figures 2 and 3; Figure 5 shows two input elements of the player position validation interface provided which can adjust the behaviour of the player detection and tracking system; and 5 Figure 6 shows a schematic block diagram of computer executable instruction modules used to implement the player position validation interface. DETAILED DESCRIPTION INCLUDING BEST MODES FOR CARRYING OUT THE INVENTION 5 Figure 1 shows a graphical schematic of the components employed by a player position detection and tracking system. The player position detection and tracking system includes an image capture device in the form of a digital video camera 1. The video camera 1 is positioned so as to record a succession of video images, such as video image 2, over time of a field of play of a cricket game. 10 The video images recorded by the video camera 1 are supplied, in real time, to a computer system 3. The computer system 3 is employed to run computer executable instructions which implement a player position determination and tracking system. The computer system 3 is further employed to run computer executable instructions which implement a validation interface. The computer executable instructions are 15 typically stored on a computer readable medium. A computer readable medium having such computer executable instructions stored thereon provides a computer product. The instructions executed by the computer system 3 firstly processes the video images received from the video camera 1 to detect the position of players on the field, 20 and then track the players in order to update their respective positions. Those skilled in the art may appreciate that a range of image processing techniques may be employed to implement player position determination. For example, in one instance individual objects may be identified through subtracting a prior background frame from a current frame to identify objects which are moving. Alternatively contour tracking 25 may be employed to define the outline of a potential object, or alternatively edge detection techniques or segmentation methods may be employed. The output of the 6 player position determination is a list of potential candidate objects. Once candidate objects have been determined through the above techniques additional tracking functionality is employed through comparisons of successive frames to identify the presence of a previously identified candidate object in the new 5 or current frame. The accuracy of such automated detection and tracking systems is greatly affected by the clarity of the video images, players, shadows on the field, etc. Also, a number of non-player objects may be detected. Such objects may for example include other people on, or next to, the field. Such objects may also include birds or wind blown 10 litter moving across the field. Accordingly, the accuracy of the automated detection and tracking system could be improved through input from an operator. The operator has knowledge of which objects represent players, and which objects are non-players. That input may be employed and correct detection and/or tracking errors where and when appropriate. 15 Furthermore, intersections of the pixels representing respective players may also lead to such tracking errors. This may be particularly significant when a player and an umpire cross paths, as such may lead to the tracking algorithm incorrectly associating the umpire with a player. Alternatively, in the case of two players crossing paths, the tracking algorithm may end up tracking the movements of a single player, as opposed 20 to the two players tracked previously. The present invention therefore provides an operator validity interface allowing the operator to validate candidate player positions detected and tracked by the detection and tracking system. Therefore, after the list of candidate objects has been determined, the validation 25 interface of the present invention displays on a display of the computer system 3 a 7 graphical representation of the positions of those candidate objects. The validation interface allows an operator 4 to validate the candidate objects as valid player positions. This input from the operator 4 is in turn supplied back to the player position determination and tracking system to trigger the tracking of these validated 5 player positions. The input provided by the operator through the validation interface also allows valid or corrected player position data to be collated. Lastly, the validated player position data (consisting of a set of X, Y co-ordinates for each valid player position) is supplied to a graphics rendering system. This graphics rendering system can then present a graphical representation 5 of the validated 10 player position data. Figure 2 shows a flowchart illustrating a method 20, implemented through computer executable instructions, to implement the validation interface in accordance with a preferred embodiment. The method 20 starts in step 21 when the validation interface receives as input a 15 plurality of candidate player positions from the detection and tracking system. These candidate player positions are then, in step 22, overlaid on the video image of the playing field used to determine the candidate player positions, and displayed on the display of the computer system 3 (figure 1). An example of a video image with the candidate player positions overlaid is illustrated in figure 3 wherein the candidate 20 player positions are represented through circular objects. These candidate player positions include fielding players in addition to the batsmen. Umpires, other people on the field, or other items may also be detected as candidate player positions. Instead of overlaying the candidate player positions onto the video image, the player positions may be displayed on an augmented reality display (also known as a heads 25 up display), which is a transparent display which displays the candidate player positions without obstructing the operators view, thereby allowing the candidate player 8 positions to be overlaid over the operator's view of the field. Next, in step 23, to the method 20 determines whether the operator 4 has previously entered data pertaining to static objects present within the view of the playing field. If such static object data has not been previously entered, step 24 prompts the operator 5 4 to trace the outline of any static object present within the view of the playing field. Such static objects allow player positions to be calculated relative to these static objects. Following step 24, or if it is determined in step 23 that static object data has previously been entered, processing continues to step 26 where the method 20 receives validity 10 indicators in association with candidate player positions. Preferably the validity indicators are received through the operator 4 moving a pointer of a graphical pointing device, such as a computer mouse, over each candidate position illustrated, and validating positions through depressing the buttons of the graphical pointing device. For example, a left mouse button click may be used to provide a positive validity 15 indicator, whereas a right mouse button click may be used to provide a negative validity indicator. Alternatively, the operator may only indicate which candidate positions are invalid, with all other candidate positions being assumed to be valid. In yet another alternative implementation only valid candidate positions are verified by the operator 4, with all remaining candidate positions being considered invalid. 20 Following step 26 each candidate player position has associated there with a validity indicator. After these validity indicators have been received the method proceeds to step 27 where it is determined whether the operator 4 is dissatisfied with the performance of the detection and tracking system, and in particular the number of candidate player 25 positions presented to the method 20 in step 21. If the operator 4 indicates dissatisfaction with the performance of the detection and 9 tracking system, processing continues to step 28 where the operator is presented with an interface for adjusting, or modifying, behavioural parameters employed by the detection and tracking system. In the preferred implementation the behaviour parameters are adjusted through adjusting the position of a pair of sliders 51 and 52, 5 as illustrated with respect to figure 5. The first of these sliders 51 modifies a contrast ratio to control the sensitivity of the detection and tracking system and hence the number of candidate player positions which will be presented to the operator 4. The second slider 52 labelled "Tracking length multiplier" determines the maximum speed at which a player is expected to move and hence will eliminate from consideration any 10 objects from being tracked which move at high velocity. In a preferred embodiment the interface provided may also allow an operator to indicate the expected height or size of players at particular locations within the image of the playing field recorded. Players on the far side of the field to the camera 1 will be represented by a smaller number of pixels than players closer to the camera 1. This facility can therefore allow 15 the operator 4 to define a size or height expected for players at various distances from the camera 1. Those skilled in the art would appreciate that other types of user controls may be used in alternative embodiments of the present invention. For example, pull down menus, text or numeric character entry boxes, or potentially voice command 20 recognition systems may all be employed to implement the entry of such behavioural modification parameters. Furthermore, as would be appreciated by those skilled in the art, a range of different parameters may also be adjusted in addition to the tracking multiplier and contrast threshold parameters shown with respect to figure 5. If the method 20 does not receive in step 27 an indication of dissatisfaction with the 25 performance of the detection and tracking system, or following step 28, the method 20 proceeds to step 29 where a final set of valid player positions is collated based on the positive and negative validity indicators entered by the operator 4 in step 26. This 10 collated set of valid player positions is then forwarded to an output stage of the validity interface, which in a preferred embodiment transmits this data to a graphics rendering system. An example of the output of such a graphics rendering system is illustrated with respect to figure 4, which provides a virtual "top down" view of the playing field 5 with each of the valid player positions determined shown by a circle. This rendering system can also present graphics of the static field objects entered by the operator in step 24. This collated set of valid player positions is also forwarded to the detection and tracking system to trigger the tracking of these validated player positions in 10 subsequent video images recorded of the playing field. Steps 21 to 29 are continuously repeated allowing the operator 4 to continuously refine the candidate player positions. Those skilled in the art would also appreciate that the specific set of instructions and steps discussed above need not be considered essential to all potential 15 implementations of the present invention. Those skilled in the art would appreciate that various design modifications may be employed from description provided above while still falling within the scope of the invention. Figure 6 shows a schematic block diagram of computer executable instruction modules used to implement the validity interface 60 as discussed with respect to 20 figure 2. The validity interface 60 is used to capture from the operator 4 validity indicators 61 (step 26, figure 2), static object data 62 (step 24, figure 2) and parameter settings 63 (step 28, figure 2). As can be seen from figure 6 the user interface 60 engages with an image processing unit 70 which receives a sequence of captured video images 71 over time. The image 25 processing unit 70 performs the detection and tracking processes described above. The user interface 60 receives automated player position identification and tracking 11 information from the image processing unit 70, and supplies to the image processing unit 70 the information and settings captured in steps 24 and 28. The user interface 60 also passes to the image processing unit 70 the validity indicators associated with the candidate player positions. The user interface 60 also provides the collated set of 5 valid player positions to output stage 72. As would be appreciated from the above, the workload of the operator 4 is reduced by the input from the detection and tracking system. Only detection and tracking errors are corrected. This allows for the timely delivery of player position data. The present invention may provide many potential advantages over the prior art. 10 The present invention provides corrected player position data substantially in real time, concurrent with a sports event being played. In particular the present invention may be used to validate automatically captured player position data. This data may then be used by broadcast television networks to render graphics to be broadcast to audiences in the time between balls of a cricket game (for example) to illustrate the 15 positions taken and movements made by players in or near real time. This real time processing provided by the present invention allows frequent outputs of corrected player position data in timeframes suitable for rendering of representative graphics for a broadcast audience. The player position validation interface provided allows a single operator to monitor 20 the performance of a player position determination and tracking system which receives an image feed from the single camera 1 only. When used with cricket games, errors introduced through the use of the single camera 1 are readily corrected in real time by the operator 4 using the interface of the present invention to initially validate the positions of eleven fielding players of a cricket team. Furthermore, the 25 tracking functionality which is employed based on these validated positions in turn reduces the amount of work required of an operator during play. The combination of 12 the interface provided and such tracking systems leaves the operator 4 only correcting errors introduced by the tracking algorithm, as opposed to independently verifying player positions after each iteration of the tracking process. Aspects of the present invention have been described by way of example only and it 5 should be appreciated that modifications and additions may be made thereto without departing from the scope thereof. For example, the player position determination and tracking may be implemented on a separate system to the system implementing the validation interface. 13

Claims

1. A method adapted to capture and present candidate object positions within an automated position detection and tracking system, said method comprising: obtaining real time video images from a single image capture device; executing algorithms for setting initial candidate object position detection and tracking elements; processing said candidate object positions, substantially in real-time; overlaying the initial candidate object positions identified on an image captured previously; allowing an operator to modify the candidate object position detection and tracking elements; allowing an operator to independently add static objects to be graphically presented, and used in tracking candidate object positions; allowing an operator to manually validate or invalidate candidate objects; displaying a graphical representation of validated candidate objects.

2. The method according to claim 1 wherein said method optionally comprises displaying the object positions on an augmented reality display.

3. A validation interface adapted to capture and present candidate object positions within an automated position detection and tracking system, said interface comprising: real time video images from a single image capture device; 14 algorithms for setting initial candidate object position detection and tracking elements; means for overlaying the initial candidate object positions identified on an image captured previously; an image processing unit capable of processing candidate object positions substantially in real-time wherein the image processing unit also comprises means to allow an operator to independently add static objects to be graphically presented, and used in tracking the candidate object positions; means for allowing an operator to modify the candidate object position detection and tracking elements; means for allowing an operator to manually validate or invalidate candidate object positions; means for displaying a graphical representation of validated candidate object positions.

4. A validation interface according to claim 3 wherein said interface optionally comprises a means for displaying the objects on an augmented reality display.

5. A computer product having stored thereon computer executable instructions for effecting a method adapted to capture and present candidate object positions within an automated position detection and tracking system, said method comprising: obtaining a real time video images from a single image capture device; executing algorithms for setting initial candidate object position detection and tracking elements; 15 processing said candidate object positions, substantially in real-time; overlaying the initial candidate object positions identified on an image captured previously; allowing an operator to modify the candidate object position detection and tracking elements; allowing an operator to independently add static objects to be graphically presented and used in tracking candidate object positions; allowing an operator to manually validate or invalidate candidate object positions; displaying a graphical representation of validated candidate object positions.

6. A method for capturing and presenting candidate object positions within an automated position detection and tracking system, said method being substantially as described herein with reference to the accompanying drawings.

7. Apparatus for capturing and presenting candidate object positions within an automated position detection and tracking system, said apparatus being substantially as described herein with reference to the accompanying drawings. 16