GB2380883A

GB2380883A - Location and identification of participants in a sporting event by means of optically readable tags

Info

Publication number: GB2380883A
Application number: GB0213955A
Authority: GB
Inventors: Julian Nolan Gannaway
Original assignee: Roke Manor Research Ltd
Current assignee: Roke Manor Research Ltd
Priority date: 2001-06-20
Filing date: 2002-06-18
Publication date: 2003-04-16
Anticipated expiration: 2022-06-18
Also published as: GB2380883B; GB0213955D0; GB0115042D0

Abstract

A system for identifying and locating moving participants 6 in a sporting event comprises tags 7 mounted on each participant providing a data signal that is optically readable and distinctive of the participant it serves to mark. A video camera 2 is directed at the tags and a light source illuminates the tags so that a modulated optical signal is generated by a light reflective portion of the tag. A data recognition and processing means 5 is provided at the output of the video camera to derive the identity and location of each participant 6. The reflective portion of the tag may be modulated using liquid crystal technology or electro sensitive coatings. The system may include active tags producing short pulses of infra red light and the video camera may include an IR filter to facilitate detection. The system may further comprise static objects provided with tags to act as reference points for determining the position of moving participants.

Description

SYSTEM FOR DETECTING, IDENTIFYING AND LOCATING A PLURALITY OF MOVING PARTICIPANTS IN A SPORTING EVENT This invention relates to a system for detecting, identifying and locating a plurality of moving participants in a sporting event, in particular for use at horse race meetings.

Identification of the participants at sporting events, as required by television commentators for example, can in some cases present something of a problem and in particular, the identification of runners or riders at horse racing events can be very problematic, especially during a race.

In accordance with a first aspect of the present invention, a system for detecting, identifying and locating a plurality of moving participants in a sporting event, comprises an identity tag mounted on each participant; and at least one video camera directed at the tags; wherein each tag is arranged to provide a data signal which is optically readable and distinctive of the participant which it serves to mark; the system further comprising a light source for illuminating the identity tags, such that a modulated optical signal is generated by each tag; wherein the light source is remote from the tag and the modulated signal is generated by modulation of light reflectivity of a portion of the tag; and data recognition and processing means for processing the output of the video camera to derive an identity and location of each moving participant.

The system of the present invention facilitates the identification of participants at sporting events, such as horse racing meetings. The optically readable data signal is provided by modulation of the light reflectivity of a portion of the tag. The light may be modulated at a relatively slow rate such that the pulses can be read through the frame rate of the camera e. g. 10 pulses per sec. for a 25 Hz frame rate.

The term light when used herein includes light in the visible spectrum or in the non-visible spectrum as judged by the human eye and thus'optically readable signals' may be light signals in the visible spectrum or light signals in the non-visible spectrum.

Preferably, a reflective portion of the tag is modulated using liquid crystal technology or electro-sensitive coatings, for example the operating spectrum may be in the visible or in the non-visible IR range.

Preferably, the system further comprises an LED which produces short pulses of infra red (IR) light, i. e. an'active tag'and the video camera includes IR filter means to facilitate its detection.

Preferably, the system further comprises static objects provided with tags to act as reference points for determining the position of the moving participants.

In general the participants are animate and in the case of a horse race meeting, comprise the runners or riders, the position of which, relative to the reference points, is determined by the data recognition and processor means.

Preferably, the video camera is mounted on a crane, access platform, a tethered balloon or aerostat. A plurality of cameras may be used to afford a required area of coverage, one or more of the cameras being selected as appropriate to provide the video signal.

Alternatively the at least one video camera is mounted on a moveable platform, such as a free flying aerostat, controlled as necessary to follow and track the objects to be identified.

Preferably, the camera comprises servos which lock on, to a tags or tags so as to compensate for jitter.

Preferably, the camera is arranged to track the average speed of moving participants.

Preferably, the system is arranged to identify a pixel group defining the visible outline of an object and to counter jitter by guiding this group of pixels around the last known pixel containing a tag.

Preferably, the video camera is coupled to the data recognition and processor means via a radio link.

Preferably, the data signal provided by each tag comprises a plurality of bits which define a code distinctive of the tag with which it is associated.

Preferably, data is sent as a series of light pulses, the bit rate of the chosen code being arranged to be small relative to the camera frame rate.

Preferably, the chosen code is arranged not to comprise a relatively long series of successive'Os.

Preferably, the tags are operated sequentially to provide a similar optical data signal, each tag being identifiable in dependence upon the position which the optical data signal provided occupies in the sequence.

In accordance with a second aspect of the present invention a race horse discrimination device for discriminating between horses in a horse race comprises a system according to the first aspect, wherein the participants comprises at least one of race horses and riders.

One embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings in which; Figure 1, is a somewhat schematic side view from above of a system for identifying and tracking the runners/riders at a horse race track; Figure 2, is a somewhat schematic block diagram of a receiver/data processor which forms a part of the system shown in Figure 1; Figure 3, is a flow diagram which illustrates operation of the an image processor shown in Figure 2 and; Figure 4, is a video camera frame view, of a portion of a horse race track, wherein individual pixels are shown schematically.

Referring now to Figure 1, an oval race track 1, is viewed from above by a video camera 2, mounted on an airship 3, which can be controlled as necessary to facilitate the tracking of horses/jockeys racing around the track 1, each of which is arranged to carry an optically identifiable tag. The tags are passive and comprise a liquid crystal reflector or the like which is modulated by a distinctive coded signal for identification purposes. Assuming that the video camera 2, operates at a frame rate of 25Hz, the bit rate of the coded signal must be below about lOHz to avoid aliasing problems, which would allow the use of an 8 or 10 bit code to identify each horse/rider.

Signals carrying video data thus produced, are transmitted via a radio link 4, to a receiver and data processor 5, stationed on the ground. Additionally, active tags and an IR signal transmitter arranged to transmit a distinctive identifying coded signal may be provided.

In order to identify a horse/rider 6, the horse or the rider is arranged to carry a tag 7, in such a manner that it can be readily viewed from above by the camera 2, for identification purposes. In order to determine the position of the horse/rider 6, on the track 1, a number of reference beacons 8, are provided in spaced apart relationship around the track, which beacons 8, are each identified by means of a distinctive tag, similar to the tag 7, but arranged each to generate their own unique identification code.

Referring now to Figure 2, the receiver/data processor 5, of Figure 1, comprises a radio receiver 9, an image processor 10, which processes the received video signal as

derived from the video camera 2, with reference to data stored in a database 11. Thus data corresponds to, and serves to identify the various reference beacons 8, and the various horses/riders 6, whereby their relative positions can be computed and communicated via a server 12, to those requiring this information, such as television commentators, or TV program directors, for example.

Operation of the image processor 10, comprises some basic steps as shown in Figure 3, wherein identification of outlines such as a horse/rider 13, and the presence of flashing pixels indicating flashing tags 14, is effected using well known techniques, comprising shape recognition and pulse detection techniques respectively. The position of these features is then established 15, and the identity of the of the flashing pixels is established 16, to provide continuously, data appertaining to position/identity to update a database 17, arranged to feed the server 12, which is shown also in Figure 2.

Thus or each video frame, the outline of horses/riders are identified from the optical image and the position of each track side beacon is also identified. Within each of these outlines, a small group of pixels are searched over a number of frames for a pixel which changes brightness in accordance with a recognisable code. The code pattern identifies each horse/rider and each track side beacon. The combination of the optical outline and the pixel containing the coded sequence, allow the position of the horse/rider relative to the track side beacons to be identified precisely.

Thus in the schematic camera view of Figure 4, wherein two horses/riders 18, and 19, and three reference beacons 20,21, and 22, are shown in a video camera field of view defined by 240 pixels in a matrix 12 x 20, since the horses/riders 18,19, and the beacons 20,21, 22, can be identified by their respective tags, and since the beacon 20,21, 22, positions are known, the relative positions and identities of the horses/riders 18,19, are relatively simple to establish.

Thus more generally, TV cameras may be used to provide a simple, of providing location details of the tagged participants (players or entrants) at any sporting event, particularly if the cameras are mounted on an elevated platform so as to provide a plan view of the event. A plan view of the participants would be provided from cameras at a height of between a hundred and a thousand feet, mounted as appropriate on cranes or access platforms, or tethered to balloons or aerostats which each cover a part of the course, which is thereby viewed at an oblique angle, or alternatively mounted on a moveable platform or free flying aerostat, movement of which could be controlled to follow the participants around, providing a view from above them. This

approach has the advantage of minimising the infrastructure requiring maintenance on the ground, and is capable of being taken to any event and set up at short notice.

Whilst the position can be found from a TV camera picture, it is not normally so easy to determine the identity of each participant. However by attaching an optical tag to each participant which modulates the reflectivity of an area of the tag with a sequence of pulses at a rate that can be read by observing it through a video camera or similar optical sensor, or additionally flashes, the identities of each participant can be established quite simply.

With the additional active tags, it is possible to synchronise the timing of an electronic shutter in the camera to the tags'flashing so as to improve the signal to noise ratio or reduce the LED power consumption. The tags and the camera could contain a simple radio receiver which receives timing signals from a local transmitter.

Alternatively, with just passive tags, each tag could be made to modulate the reflectivity of an area, say 5 cm square, using liquid crystal technology or electrosensitive paints for example, which would switch from black to white to convey data bits of a code. This has the benefit of taking advantage of bright ambient light, rather than having to compete with it, as in the case of an LED and could operate either in the visible or IR spectrum.

Better performance could be achieved by using an optical retro-reflector as part of a modulated reflectivity tag, and a laser, or other IR, illuminator mounted adjacent to the camera. This would reflect most of the light from the illuminator back in the direction of the camera, making the target much brighter than other objects lit by sunlight so that it would stand out from them.

A system may be provided to cater for jitter in the orientation of a platform/camera comprising servos which could lock on, either to tags on the participants, or fixed beacon tags at the side of a track. As participants will be harder to identify than track side beacons, it might be more effective to lock camera tracking to the average speed of the participants as they progress around the track, so that they are nominally stationary in the field of view. The camera servo would thus need to make relatively slow changes only.

It is likely that the tags would not appear in the same pixel every frame due to camera shake, so it could be arranged to identify the visible outline of a participant in each camera image and to counter jitter by guiding this group of pixels around the last known one containing the tag. The tag pixel could then be identified as a relative

position within that outline. It would be desirable to limit the selection of pulse codes to those that do not have a long series of'0's, as in this case it is more difficult to see which pixel the tag is in, if it is not'ON'.

The system could either have one camera tracking the leading participants in a race say, or a number of cameras rather like an Insect's Eye', with a large number of fixed cameras to increase the field of view. It might use several cameras in a line, all on the same mechanical tracking mount, to provide coverage of a long section of the track.

Various modifications may be made to the system as just before described without departing from the scope of the invention and for example the system may be used in applications other than sporting events. Also, various modes of operation are envisaged. For example, each tag could be turned'ON'for several successive frames, rather than pulsed in a code pattern, so that each provides a similar optical data signal, the tags being energised sequentially, either synchronously with reference to absolute time or asynchronously, each tag being identifiable in dependence upon its position in the sequence. In another mode, for at least some of the time, all tags may be left on every frame to facilitate more accurate tracking, and a still further option might comprise a combination of any of the aforesaid modes of pulsing as herein described, the operational mode used being chosen in accordance with the application in view.

Claims

1. A system for detecting, identifying and locating a plurality of moving participants in a sporting event, the system comprising an identity tag mounted on each participant; and at least one video camera directed at the tags; wherein each tag is arranged to provide a data signal which is optically readable and distinctive of the participant which it serves to mark; the system further comprising a light source for illuminating the identity tags, such that a modulated optical signal is generated by each tag; wherein the light source is remote from the tag and the modulated signal is generated by modulation of light reflectivity of a portion of the tag; and data recognition and processing means for processing the output of the video camera to derive an identity and location of each moving participant.

2. A system according to claim 1, wherein a reflective portion of the tag is modulated using liquid crystal technology or electro-sensitive coatings.

3. A system according to claim 1 or claim 2, wherein the tag further comprises an LED which produces short pulses of infra red (IR) light and the video camera includes IR filter means to facilitate its detection.

4. A system according to any preceding claim, further comprising static objects provided with tags to act as reference points for determining the position of the moving participants.

5. A system according to any preceding claim wherein the at least one video camera is mounted on one of a crane, access platform, tethered balloon or aerostat.

6. A system according to any preceding claim, wherein the at least one video camera is mounted on a moveable platform.

7. A system according to claim 6, wherein the camera comprises servos which lock on, to a tags or tags so as to compensate for jitter.

8. A system according to claim 6 or claim 7, wherein the camera is arranged to track the average speed of moving participants.

9. A system according to any of claims 6 to 8, arranged to identify a pixel group defining the visible outline of a an object and to counter jitter by guiding this group of pixels around the last known pixel containing a tag.

10. A system according to any preceding claim, wherein the video camera is coupled to the data recognition and processor means via a radio link.

11. A system according to any preceding claim, wherein the data signal provided by each tag comprises a plurality of bits which define a code distinctive of the tag with which it is associated.

12. A system according to claim 11, wherein data is sent as a series of light pulses, z : l the bit rate of the chosen code being arranged to be small relative to the camera frame rate.

13. A system according to claim 11 or claim 12, wherein the chosen code is arranged not to comprise a relatively long series of successive'Os.

14. A system according to any of claims 1 to 10, wherein the tags are operated sequentially to provide a similar optical data signal, each tag being identifiable in dependence upon the position which the optical data signal provided occupies in the sequence.

15. A race horse discrimination device for discriminating between horses in a horse race, the device comprising a system according to any preceding claim, wherein the participants comprises at least one of race horses and riders.

16. A system for detecting, identifying and locating a plurality of moving participants in a sporting event as hereinbefore described with reference to the accompanying drawings.