SYSTEM AND METHOD FOR 3D OPTICAL TRACKING OF MULTIPLE IN-FLIGHT GOLF BALLS

Abstract

A system for visually tracking the trajectory of an in-flight golf ball through an x-y-z space above a driving range includes a plurality of cameras for respectively creating a video stream of the x-y-z space. Each video stream is presented on a dedicated camera focal plane with information on respective azimuth angles and elevation angles from the particular camera to the in-flight golf ball. A central computer is connected with the camera focal plane of each camera to identify a start point for the golf ball, to track its trajectory in the x-y-z space, and to filter out background clutter. A visual display is provided to show the in-flight golf ball from its start point to a target point in real time.

Claims

1. A system for visually tracking the trajectory of a single golf ball selected from a plurality of in-flight golf balls, in real time, which comprises: an n number of cameras (1.sup.st, 2.sup.nd, 3.sup.rd . . . n.sup.th), wherein the cameras are surveyed into a position on the periphery of a driving range, with the first and second cameras positioned to define a base line having a length L therebetween, and to establish a horizontal center line midway between the first and second cameras perpendicular to the base line, wherein the base line and the center line establish an x-y plane in a three dimensional x-y-z space for the driving range; a central computer for receiving a respective video signal from each of the n number of cameras, wherein the video signal includes an azimuth angle .sub.n and an elevation angle .sub.n for the golf ball in the x-y-z space relative to the surveyed position of the n.sup.th camera in the x-y-z space, wherein the computer continuously updates an in-flight x-y-z coordinate position for the golf ball in the x-y-z space based on mathematical manipulations of data in the video signal from the n number of cameras; and a display monitor connected with the computer for visually tracking the flight path of the golf ball in the x-y-z space.

2. The system recited in claim 1 wherein the video signal from each camera comprises a plurality of pixels arranged in a camera focal plane defined by a horizontal axis and an orthogonal vertical axis, and wherein the position of a pixel on the horizontal axis of the camera focal plane corresponds to the azimuth angle .sub.n of the golf ball and its position on the vertical axis corresponds to the elevation angle .sub.n of the golf ball.

3. The system recited in claim 2 further comprising a plurality of bays for respectively launching a golf ball therefrom, wherein the bays are aligned in a tee-line parallel to the base line, wherein each bay in the tee-line is mapped into a unique set of pixels on a camera imaging focal plane.

4. The system recited in claim 3 wherein a range R is established from a camera to a golf ball location in a selected bay, and the range R is determined at the time the golf ball is launched and is established by reference to a calibration of pixels in the x-y plane between the camera and the golf ball in the bay, to establish an accurate association of the camera with the bay for subsequent 3-D tracking of the in-flight trajectory of the golf ball.

5. The system as recited in claim 4 further comprising a High Speed Video Graphics Processor (HSVGP) for simultaneously receiving video signals from the n number of cameras to filter from the video signals stationary background clutter, objects having a predetermined speed below that of an in-flight golf ball, and other golf balls to reveal only the golf ball launched from the selected bay in the camera focal plane.

6. The system recited in claim 2 wherein cameras are aligned on both sides of the driving range opposite the horizontal center line to establish a plurality of opposed pairs of cameras, wherein the respective fields of view for cameras in a pair cover a same sector of the driving range, and they overlap with the fields of view of cameras covering an immediately adjacent sector of the driving range.

7. The system as recited in claim 6 wherein the computer creates a cue of golf balls from each in-flight trajectory in a sector, and sequentially transfers the golf balls in the cue, in their order, to cameras in the adjacent down-range sector to indicate where and when the golf ball should arrive in the down-range sector for further tracking through the x-y-z space.

8. The system as recited in claim 7 wherein the central computer correlates each golf ball trajectory with a particular bay on the tee line and with a predetermined target in the driving range.

9. The system as recited in claim 8 wherein the central computer detects whether two golf balls collide in flight, and estimates post-impact trajectories to provide continued multi-ball disambiguation.

10. A system for visually tracking the trajectory of a single golf ball selected from a plurality of in-flight golf balls, in real time, which comprises: an m number of bays arranged contiguously along a tee-line, wherein golf balls can be individually launched in a random manner, from any bay at any time, into an x-y-z space for flight on a respective trajectory therein; an n number of cameras for respectively creating an n number of video streams of the x-y-z space, wherein each video stream from each camera covers a predetermined sector of the x-y-z space from a unique perspective, and wherein each video stream is presented on a respective camera focal plane; a central computer for receiving the plurality of video streams for identifying a start point in a predetermined bay on the camera focal plane of each video stream, for establishing when a golf ball is launched from the start point onto its trajectory through the x-y-z space, and for filtering stationary background clutter and the trajectories of other golf balls from the camera focal plane; and a visual display positioned in each bay and connected to the central computer for showing the trajectory in real time of the golf ball launched from the particular bay and through the x-y-z space from its start point in the bay to a target end point.

11. The system recited in claim 10 wherein the camera focal plane from each camera comprises a plurality of pixels arranged relative to a horizontal axis and an orthogonal vertical axis, and wherein the position of a pixel on the horizontal axis of the camera focal plane corresponds to the azimuth angle .sub.n of the golf ball, and its position on the vertical axis corresponds to the elevation angle .sub.n of the golf ball, and wherein each bay in the tee-line is mapped into a unique set of pixels on a camera imaging focal plane,

12. The system recited in claim 11 wherein a range R is established from a camera to a golf ball location in a selected bay, wherein the range R is determined at the time the golf ball is launched and is established by reference to a calibration of pixels in the x-y plane between the camera and the golf ball in the bay, to establish an accurate association of the camera with the bay for subsequent 3D tracking of the in-flight trajectory of the golf ball.

13. The system recited in claim 11 wherein the computer continuously updates an in-flight x-y-z coordinate position for the golf ball in the x-y-z space based on mathematical manipulations of data in the video streams from the n number of cameras.

14. The system recited in claim 10 wherein cameras are positioned to establish a plurality of opposed pairs of cameras, wherein the respective fields of view for cameras in a pair cover a same sector of the golf ball in-flight trajectory, and they overlap with the fields of view of cameras covering an immediately adjacent sector of the golf ball in-flight trajectory.

15. The system recited in claim 14 wherein the computer creates a cue of golf balls from each in-flight trajectory in a sector, and sequentially transfers the golf balls in the cue, in their order, to cameras in the adjacent down-range sector to indicate where and when the golf ball should arrive in the down-range sector for further tracking through the x-y-z space.

16. The system recited in claim 15 further comprising a High Speed Video Graphics Processor (HSVGP) for simultaneously receiving video signals from the n number of cameras to filter from the video signals stationary background clutter and objects having a predetermined speed below that of an in-flight golf ball, to reveal only golf balls as moving objects in the camera focal plane.

17. The system recited in claim 10 wherein the central computer correlates each golf ball trajectory with a particular bay on the tee-line and with a projected target in the driving range.

18. The system recited in claim 10 wherein the central computer detects whether two golf balls collide in flight, and estimates post-impact trajectories to provide continued multi-ball disambiguation.

19. A non-transitory, computer-readable medium having executable instructions stored thereon that direct a computer system to perform a process for tracking the trajectory of a single golf ball in a driving range, the trajectory being selected from a plurality of in-flight golf balls in real time, the medium comprising instructions for: receiving a video stream from each of an n number of cameras; arranging a plurality of pixels from each video stream into a camera focal plane defined by a horizontal axis representing an azimuth angle .sub.n and a vertical axis representing an elevation angle .sub.n; identifying a golf ball location in a selected camera focal plane at the time a golf ball is launched into the driving range; filtering the video streams to remove stationary background clutter, objects having a predetermined speed below that of an in-flight golf ball, and other golf balls not identified in the identifying instruction, to reveal only the identified golf ball in the focal plane; calculating an in-flight coordinate location for the identified golf ball after launch, based on azimuth and elevation measurements from the cameras; continuously updating the in-flight coordinate location of the identified golf ball to create a trajectory for the identified golf ball; and presenting the in-flight trajectory of the identified golf ball for visual evaluation by a golfer.

20. The medium recited in claim 19 further comprising instructions for: detecting when two golf balls collide in flight; and estimating post-impact trajectories to provide continued multi-ball disambiguation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

[0013] FIG. 1 is a perspective view of an active driving range in accordance with the present invention at a time is;

[0014] FIG. 2 is a top plan view of the driving range showing camera fields of view and golf ball tracking sectors for the driving range;

[0015] FIG. 3A is a schematic layout of components for a preferred embodiment of the central computer of the present invention;

[0016] FIG. 3B is a schematic layout of components for an alternate embodiment of the central computer of the present invention;

[0017] FIG. 4A is a presentation of the camera focal plane in the video stream generated by the (n) camera, showing the azimuth angle .sub.n and the elevation angle .sub.n of a selected in-flight golf ball at a time t.sub.s;

[0018] FIG. 4B is a presentation of the camera focal plane in the video stream generated by the n+1 camera, showing the azimuth angle .sub.n+1 and the elevation angle .sub.n+1 of the selected in-flight golf ball at the time t.sub.s;

[0019] FIG. 5A is a geometrical presentation of azimuth angles .sub.1, and .sub.2 in the x-y plane of a selected in-flight golf ball for use in calculating values for the x and y coordinates of the golf ball at the time t.sub.s; and

[0020] FIG. 5B is a geometrical representation of the elevation angle .sub.1 for the selected golf ball in a y-z plane at the azimuth angle .sub.1 for use in calculating a value for the z coordinate of the golf ball at the time t.sub.s.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Referring initially to FIG. 1, a venue in accordance with the present invention is shown and is generally designated 10. As shown, the venue 10 includes a golf driving range 12 that is bounded by a base line 14 and a periphery 16, and which defines an x-y-z space above the turf of the driving range 12. An n number of cameras 18 are surveyed onto the driving range 12 with respective x-y-z coordinates, and are positioned at predetermined locations on the periphery 16. Further, as indicated in FIG. 1, the first camera 18.sub.(1) and the second camera 18.sub.(2) are used to define the base line 14 between them, and they also establish a length L therebetween for the base line 14. As also shown in FIG. 1, a center line 19, together with the base line 14, effectively define an x-y plane for the venue 10, and the number of cameras 18 will typically be six.

[0022] It is also indicated in FIG. 1 that each of the cameras 18 can identify an azimuth angle .sub.n and an elevation angle .sub.n which are uniquely defined by the n.sup.th camera. For example, camera 18.sub.(1) defines an azimuth angle .sub.1 and an elevation angle .sub.1 while camera 18.sub.(2) defines an azimuth angle .sub.2 and an elevation angle .sub.2.

[0023] FIG. 1 also shows that an m number of bays 20 are provided in the venue 10 for launching golf balls 22 into the driving range 12. As shown, them number of bays 20 are typically aligned along a tee-line 24 that will most often be established generally parallel with the base line 14. In this arrangement, consider a golf ball 22.sub.(5) which is launched from the fifth bay 20.sub.(5) on the tee-line 24 and onto an in-flight trajectory 26 into the x-y-z space above the turf of the driving range 12. At a selected time t.sub.s after launch, while the golf ball 22.sub.(5) is still in the air, it will be at coordinates (x-y-z).sub.(5). Importantly, at any time t.sub.s during the flight of the golf ball 22.sub.(5) the first camera 18.sub.(1) will record an azimuth angle .sub.1 and an elevation angle .sub.1. Simultaneously, the second camera 18.sub.(2) will record an azimuth angle .sub.2 and an elevation angle .sub.2. As disclosed below in detail, this concurrent recording continues until the golf ball 22.sub.(5) is either passed to another pair of cameras 18, or the golf ball 22.sub.(5) is no longer in flight. Consequently, in accordance with disclosure presented below, .sub.1, .sub.1, .sub.2 and .sub.2 are used to record and calculate the trajectory 26 from the time of launch until flight is terminated,

[0024] In FIG. 2 six cameras 18 are shown with their respective fields of view 28 superposed on each other. In detail, the fields of view 28 for the first camera 18.sub.(1) and the second camera 18.sub.(2) are shown as a cooperating pair, with their fields of view 28 outlined by solid lines. Similarly, the fields of view 28 for the third camera 18.sub.(3) and the fourth camera 18.sub.(4) are shown as a cooperating pair with their fields of view 28 outlined by dashed lines, and the fields of view 28 for the fifth camera 18.sub.(5) and the sixth camera 18.sub.(6) are shown as a cooperating pair with their fields of view 28 outlined by clash-dot lines. Thus, the fields of view 28 are all contiguous and they overlap to give redundancy in their cooperative coverage of the driving range 12. It is an important feature of the positioning of cameras 18 that their respective fields of view 28 effectively divide the driving range 12 into three sectors, 30, 32 and 34, with each sector 30, 32 and 34 covered by a pair of cameras 18.

[0025] FIG. 3A shows an arrangement of components for a preferred embodiment of the present invention which includes a central computer 36. As shown, the central computer 36 is used to receive the camera output 38 of each camera 18 from a network router 40. In this combination, each camera output 38 is fed directly to the central computer 36 and, more specifically, to a golf ball acquisition unit 42 in the central computer 36.

[0026] For a preferred embodiment of the present invention, the central computer 36 will include the golf ball acquisition unit 42, noted above, a golf ball tracking unit 44, and a golf-ball/target correlator 46. The golf-ball/target correlator 46 of the central computer 36 is connected directly with a respective display monitor 48 that is located respectively in each bay 20 on the tee-line 24.

[0027] In detail, the golf ball acquisition unit 42 of the central computer 36 is used to detect all moving golf balls 22 within the respective fields of view 28 of each camera 18. The golf ball acquisition unit 42 then uses this information to compute the location of each golf ball 22, and uniquely identify each golf ball 22 within the reference system (.sub.n, .sub.n) of each camera 18. The golf ball acquisition unit 42 also isolates identified golf balls 22 from others, by filtering out background clutter and moving objects other than the particular identified golf ball 22. Thus, the output 50 that is passed from the golf ball acquisition unit 42 to the golf ball tracking unit 44 includes multiple tracks (i.e. trajectories 26) that include a particular trajectory 26 for each identified golf ball 22.

[0028] For an alternate embodiment of the present invention, as shown in FIG. 3B, the functionality of the golf ball acquisition unit 42 can be accomplished before the output 50 in the video stream is passed to a modified control computer 36. For the alternate embodiment, the signal processing that is accomplished by the golf ball acquisition unit 42 prior to the transfer of output 50 to the network router 40 may be more cost effective. In any event, for either a preferred embodiment (FIG. 3A) or an alternate embodiment (FIG. 3B), each identified golf ball 22 can be followed separately on its in-flight trajectory 26 from the time it is launched out of a bay 20 until its flight is terminated. Essentially this is done by creating a database for each golf ball 22 that starts with its location in a bay 20 at launch. The location of golf ball 22 is thereafter continuously updated, as detected by the cameras 18, with reference to the record of the existing track it is creating in the database. The result here is a plurality of respectively resolved trajectories 26 for each in-flight golf ball 22. Collectively, this information is passed as an output 52 from the golf ball tracking unit 44 to the golf-ball/target correlator 46.

[0029] By following the trajectory 26 of a golf ball 22 in the output 52 from the golf ball tracking unit 44, the golf-ball/target correlator 46 is able to correlate the actual location where a particular trajectory 26 terminates, with an intended target location (not shown). Stated differently, the golf-ball/target correlator 46 determines the distance by which the golf ball 22 misses its intended target. Further, a video presentation of the trajectory 26 and its relation to a target (not shown) can be provided on a display monitor 48 for viewing by a golfer in the bay 20 from which the golf ball 22 is launched.

[0030] An important feature for the venue 10 of the present invention is the ability to follow the in-flight trajectory 26 of a golf ball 22 from its launch point in a bay 20 to an end point where the trajectory 26 is terminated. Structurally, the components involved in this operation are the golf ball acquisition unit 42 and the golf ball tracking unit 44 of the central computer 36. As noted earlier, each bay 20 in the tee-line 24 can be calibrated (mapped) into the video stream of selected cameras 18. Most importantly, the calibration (i.e. mapping) is done for the first camera 18.sub.(1) and the second camera 18.sub.(2). From this, it is to be appreciated that an operation of the present invention is thereafter accomplished within the reference system (.sub.n, .sub.n) of each camera 18.

[0031] With the above in mind, arid with reference to FIGS. 4A and 4B, it is to be appreciated that measurements for following each individual golf ball 22 on its respective trajectory 26 in the driving range 12 will preferably employ the use of two cameras 18. For this purpose, as noted above, the cameras 18 are organized into cooperative pairs. For example, a first camera 18.sub.(1) and a second camera 18.sub.(2) establish a cooperating pair of cameras 18 which have their respective fields of view 28 directed onto the sector 30 of the driving range 12 (see FIG. 2). Similarly, a third camera 18.sub.(3) and a fourth camera 18.sub.(4) will cover the sector 32, and a fifth camera 18.sub.(5) and a sixth camera 18.sub.(6) will cover the sector 34.

[0032] With specific consideration of the first camera 18.sub.(1) and the second camera 18.sub.(2) as a cooperating pair of cameras 18 covering the sector 30, each camera 18 will respectively record different azimuth angles as well as different elevation angles . Thus, as intended for the present invention, the first camera 18.sub.(1) will record .sub.1 and .sub.1 while the second camera 18.sub.(2) records .sub.2 and .sub.2. This data will then be sent by the respective cameras 18.sub.(1) and 18.sub.(2) on their respective video streams (video signals) to the central computer 36 for manipulation by the golf ball tracking unit 44.

[0033] By way of example, and with reference back to FIG. 1, consider the cameras 18.sub.(1) and 18.sub.(2) (i.e. n=1) as they track the golf ball 22.sub.(5) after it is launched from the fifth bay 20.sub.(5) into the driving range 12. While the golf ball 22.sub.(5) is in flight, the tracking unit 44 effectively creates focal plane 54 (FIG. 4A) from the video stream of the first camera 18.sub.(1). Specifically, as shown in FIG. 4A, the golf ball 22.sub.(5) will appear as a pixel 58 in the focal plane 54. By constructing the focal plane 54 so that its horizontal axis 60 corresponds to azimuth angles and its vertical axis 62 corresponds to elevation angles the angles .sub.1 and .sub.1 can be determined relative to the first camera 18.sub.(1) at any time t.sub.s. Similarly, as shown in FIG. 4B, the golf ball 22.sub.(5) will appear at the same time t.sub.s as a pixel 64 in the focal plane 56. By constructing the focal plane 56 so that its horizontal axis 66 corresponds to azimuth angles and its vertical axis 68 corresponds to elevation angles , the angles .sub.2 and .sub.2 can be determined relative to the second camera 18.sub.(2). The values for .sub.1, .sub.1, .sub.2 and .sub.2, can then be used to effectively track the trajectory 26 for the golf ball 22.sub.(5). This can be done in either of two ways.

[0034] One way for tracking a golf ball 22 in accordance with the present invention is to establish a range R from a camera 18 (e.g. cameras 18.sub.(1) and/or 18.sub.(2)) to a golf ball 22 at its location in a selected bay 20. In this case, the range R is established at, or prior to, the time the golf ball 22 is launched. As disclosed above, this is done by calibrating (referencing) pixels 64 from the golf ball 22 from a selected bay 20 with the video streams of the cameras 18 (e.g. cameras 18.sub.(1) and/or 18.sub.(2)). The result here is an accurate association of the cameras 18 with the bay 20 for subsequent 3-D tracking of the in-flight trajectory 26 of the golf ball 22.

[0035] In an alternate embodiment, a mathematical manipulation for the coordinates of a golf ball 22 in x-y-z space at any point in time t.sub.s on its flight trajectory 26, is based on known geometrical values of the system. In detail, these geometrical values are: 1) values for an azimuth angle .sub.n and an elevation angle .sub.n which are measured respectively from each of the n numbered cameras 18; 2) the length L of the base line 14 between the first camera 18.sub.(1) and the second camera 18.sub.(2); and 3) the distance x.sub.m of a bay 20 along the base line 14 from the first bay 20.sub.(1), where there are an m number of bays. For these manipulations, azimuth .sub.n and elevation from .sub.n for each camera 18, and the distance L are always known at any given time t.sub.s during the flight of the golf ball 22. Thus, at a given time t, the coordinates of a golf ball's position in x-y-z space can be determined using the video signal (.sub.n, .sub.n) from the first and second cameras 18.sub.(1) and 18.sub.(2) and physical measurements from the driving range 12 (e.g. L). Manipulations will proceed as follows: [0036] With reference to FIG. 5A and the x-y plane: [0037] y/x.sub.m=tan .sub.1; also [0038] y/(Lx.sub.m)=tan .sub.2; therefore [0039] y=x.sub.m tan .sub.1=(Lx.sub.m) tan .sub.2; and [0040] in the equation x.sub.m tan .sub.1=(Lx.sub.m) tan .sub.2, only x.sub.m is unknown; thus [0041] solve for x.sub.m. [0042] From the above: [0043] y=x.sub.m tan .sub.1 where only y is unknown; thus [0044] solve for y. [0045] Still in the x-y plane: [0046] x.sub.m.sup.2+y.sup.2=k.sup.2 where k is the distance between the first camera 18.sub.(1) and the projection of the golf ball 22 onto the x-y plane; [0047] k then equals the square root of x.sup.2+y.sup.2; and [0048] with reference to FIG. 5B and a y-z plane where k is located, z/k=tan .sub.n, or z=k tan .sub.n; thus solve for z.

[0049] As intended for the present invention, the same mathematical manipulation can then be made during the entire flight of the golf ball 22. Importantly, the golf ball 22 can be passed off from the cameras 18 covering sector 30 to the cameras 18 covering sector 32 and further, if needed to the cameras 18 covering the sector 34.

[0050] While the particular System and Method for 3D Optical Tracking of Multiple In-Flight Golf Balls as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.