WO1995010337A1

WO1995010337A1 - Method for detecting offside situations in football and system for implementation thereof

Info

Publication number: WO1995010337A1
Application number: PCT/FR1994/001194
Authority: WO
Inventors: Thierry Klein
Original assignee: Thierry Klein
Priority date: 1993-10-15
Filing date: 1994-10-14
Publication date: 1995-04-20
Also published as: FR2711069A1

Abstract

A method for detecting offside situations in football involves detecting the position of each player (1 to 11 and 21 to 31) on the pitch, emitting a triggering signal when an offside situation occurs, comparing the position of the forwardmost player of the attacking team with the positions of the two rearwardmost players of the defending team, and generating a signal in the event of a positive comparison when the triggering signal is emitted.

Description

METHOD FOR DETECTING OUT OF PLAY SITUATIONS IN A FOOTBALL GAME AND INSTALLATION FOR IMPLEMENTING SAID METHOD.

The present invention relates to a method for detecting offside situations in the game of football and installation for the implementation of said method.

Offside situations are assessed by the referee, based on the instructions of the linesman.

This method of assessment leaves possible errors, either due to a poor evaluation of the relative position of the players by the linesman, or by the lack of coordination between the referee and the linesmen.

The object of the present invention is to remedy these drawbacks by proposing a method for detecting offside situations in the game of football which makes it possible to reduce or even eliminate refereeing errors, and to provide assistance to the referee on field.

The method according to the invention consists in implementing the following steps:

- detecting the position of each player on the field;

-the issuance of a trigger signal at the time of judgment of the offside situation;

- comparison of the position of the most advanced player of the attacking camp compared to the positions of the two most distant players of the defending camp; the emission of a signal in the case where said comparison is positive at the time of the emission of the trigger signal. Advantageously, the emission of the trigger signal is carried out by a manual action on the contactor of a portable box comprising a transmitter.

According to a first variant, each of the players on the field is equipped with an identifiable transmitter, the field being equipped with goniometric receivers connected to a computer carrying out

1 exploitation of the signals for the storage in real time of the position of each of the players equipped with a transmitter. According to a second variant, a continuous image of the terrain is acquired by means of at least one camera, and the video signal is processed to determine the positions of each of the players. The invention also relates to an installation consisting of: a plurality of portable transmitters, each transmitting a specific signal, carried by each of the players; - at least one fixed goniometric receiver;

- a calculator for the real-time calculation of the position of each of the players as a function of the signals generated by the goniometric receiver;

- a portable transmitter comprising a means of initiating the phase of analysis of the offside situation;

a display means for displaying the result of the analysis.

According to a first variant, the installation for detecting off-game situations in the game of football consists of:

- at least one camera

- a calculator for the real-time calculation of the position of each of the players as a function of the signals generated by the goniometric receiver; - a portable transmitter comprising a means of initiating the phase of analysis of the offside situation;

a display means for displaying the result of the analysis.

The invention will be better understood on reading the description which follows, referring to the appended drawings relating to nonlimiting embodiments, where: - Figure 1 shows a schematic view of the football field equipped for the implementation of the method according to the invention.

Description of a first embodiment concerning detection by σoniometry. The principle of the system is as follows:

- each player (1 to 11) of the defending camp and each player (21 to 31) of the attacking camp is equipped with a UHF transmitter,

- goniometric receivers (12, 13) make it possible to locate the directions of the transmitters,

- the system is triggered by the referee by means of a remote control (20) which signals the instant when the processing station (14) must judge offside. - the processing station (14) (14) receives as input the triggering commands sent by the referee and the information on the position of the players sent by the goniometric receivers.

- on receipt of the referee's order, the processing station (14) analyzes the position of the players of the two teams on the field in order to determine whether a player (21 to 31) is out of play.

- the result of one analysis is sent to a display system (15 to 18) enabling it to be reported to the referee and the public.

The principle of the invention is: - the triggering of the instant of the offside judgment by the referee, by means of a remote control (20),

- the automatic supply and display of a result in "real time" (the result is displayed in less than a second) thanks to a positioning of the players by goniometry.

The system is broken down into: a remote control triggered by an arbiter (20);

- transmitters fitted to all players (1 to 11 and 21 to 31);

- a goniometric reception system (12, 13); - a processing station (14) making it possible to receive the signals from the remote control, the information from the direction finding system, to analyze the cases of offside and to send the results for display, - a display device (15 to 18) results in the stadium.

Description of system elements and functions

The remote control unit (20) carried by the referee comprises a radio-frequency transmitter and a modulator controlled by a button making it possible to send a coded signal. In the version described here, only one button is required. A remote control with several buttons is possible: - two buttons to signal - out of play in each camp,

- a button to cancel the triggering of the offside analysis sequence and display of the results ("reset" button). It is possible to group in this remote control a stopwatch function allowing the referee to carry only one instrument in the hand.

The transmitters worn by the players include a radio frequency transmitter circuit and a personalized modulator making it possible to identify the different signals. The power is suitable for transmission within a radius of 200 meters.

Each player (1 to 11 and 21 to 31) on the field carries a transmitter in the pocket of his jersey as well as the goalkeepers. Substitutes do not wear a transmitter. When they enter the field, the outgoing players provide them with their transmitters.

Two types of emission are possible:

- Either the 22 transmitters transmit on frequencies close but differentiable by the reception system. In this case, each player therefore has a transmission frequency.

- Either all the transmitters transmit on the same frequency but with a different modulation. In this case, each player is then identified by their code.

The installation also includes a minimum of 2 goniometric receivers (12, 13) detecting the signals transmitted by the transmitters carried by the players. To improve the accuracy of the system, a third receiver can be added.

The receivers are positioned outside the field near the corner corners. The receivers (12, 13) consist of goniometers with a fixed frame having an accuracy: - Either of the order of 1 ° for - a measurement frequency of 100 Hz. In this case, the final precision required will be reached by digital filtering on the sampled positions, carried out by the processing station (14). - Or of the order of 0.2 ° for a measurement frequency of 10 Hz. In this case, the information from goniometers allow you to directly obtain the necessary precision.

The processing station (14) (14) is composed of an acquisition module of the remote control and of a computer which performs the processing of locating the players on the field. This computer provides interface functions with the operator and with the stadium's offside signaling system. These different functions are described below. Acquisition of the remote control

The principle of processing the referee's remote control signals is as follows:

- A module makes it possible to receive the signals from the referee's remote control and in the event that the corresponding code is recognized, a digital signal is sent to the computer of the processing station (14).

- The first signal from the referee corresponds to a request to display off-games,

- after ten seconds of display and in the absence of any other command from the referee, the display is stopped and the system is ready to process a new request from the referee.

- If the referee sends a command during ten seconds, the system 1 'interprets as a cancellation of the display, the system is then ready to process without delay a new request from the referee. Positioning of players on the field the goniometers (12, 13) send by digital link the direction of emission of each of the 22 players' transmitters (1 to 11 and 21 to 31), by triangulation, the relative position of the transmitters is calculated by compared to receptors (12, 13). The position of the receivers relative to the field being perfectly known, we deduce the position of the players (1 to 11 and 21 to 31) relative to the field. The position of the receivers relative to the field is determined before the start of the match during the initialization phase.

If the goniometric receivers are sufficiently precise, the players position calculation (1 to 11 and 21 to 31) is performed at 10 Hz (frequency of sequencing of the goniometric information),

Otherwise, the positioning calculations are carried out at a higher frequency, of the order of 100 Hz, and are subject to digital filtering to improve the accuracy and achieve a target of 30 cm whatever the position of the player on the field. An option of the system consists in providing in real time the position of the players (1 to 11 and 21 to 31) for display either on a stadium screen or for television.

Analysis of players (1 to 11 and 21 to 31) out of play

The analyzes of the two halves of the terrain are carried out separately. For each half, we identify the two transmitters (players 7 and 24) closest to the corner line.

Knowing the characteristics of the transmitters, we identify the team to which each player belongs. If a player from the attacking team is one of these two players (7 and 24), there is an offside. If both players (7 and 24) are from the defending team, there is no off-side.

In all cases, the result of this search is sent to the stadium signaling system.

The treatments carried out make it possible to detect if there is an offside in the two halves of the field. The referee obviously only takes into account the display corresponding to the half of the court on which the action takes place. Check that all transmitters are working properly

The means of testing the proper functioning of the system consist in: - checking the presence of the 22 transmitters vis-à-vis the goniometers (12, 13) (if a player is expelled, the operator should notify the system)

- check the consistency of the players' positions (1 to 11 and 21 to 31) from one measure to another (the player cannot be at one end of the field, then at the other end an instant later).

If a problem is detected, the nature of the fault is displayed to the operator on a display. Sending information to the signaling system

This interface is used to control the analog connections with the signaling system.

Three signals are provided: - 1 to signal offside

- 1 to signal the absence of offside

- 1 to display nothing. Initialization

Before the start of each half, the operator enters the camp for each team in the computer and checks the assignment of the different transmitters to each team. Before kick-off, the operator can verify that the 11 players (1 to 11 and 21 to 31) from each team are on the same side. On the other hand, when installing goniometers (12, 13) in the stadium (or each time they are changed location), it is necessary to know the position of these goniometers (12, 13) compared to the field. For this, we successively position a transmitter at the six points characteristics of the terrain and note the relative position of these points with respect to the goniometers (12, 13).

This can be repeated for verification before the start of each match.

Signaling system

The signaling system consists of four small lampposts (15 to 18) located at the four corners of the corners. If there is no offside (sending the corresponding signal), the green lamp of the lamp (15 to 18) lights up. In accordance with the principle adopted, the two lampposts (15 to 18) of one camp light up simultaneously, but separately from those of the other camp.

This principle of displaying results allows players (1 to 11 and 21 to 31), the referee and the public to view the results. The green light (absence of offside) is necessary to signal the public and the players (1 to 11 and 21 to 31) that the referee has triggered the system. One option is to also display the results on a screen, either visible only from a scorer's table along the field, or on a giant screen visible to all stadium spectators.

FIG. 2 represents a schematic view of a site equipped for the implementation of the second variant embodiment of the invention.

Football offside detection by image processing

The general principle of the system according to this variant is as follows:

- a referee (20) triggers a remote control to signal the moment when the processing station (14) will have to judge the offside,

- the processing station (14) receives as input the trigger commands sent by the referee (20) and the images of a camera (or several) located above the field,

- upon receipt of the referee's order (20), the processing station (14) analyzes the image of the field and the respective positions of the players (1 to 11 and 21 to 31) of the 2 teams in order to determine whether a player is out of the game,

- the result of the analysis is sent to a display system in the stadium allowing it to be reported to the referee (20) and the public.

This second variant embodiment is based on the following principles:

- the triggering of the instant of offside judgment by the referee (20) (via a remote control),

- the supply and automatic display of a result in "real time" (the result is displayed in less than a second) via an image processing system. The system is broken down into: a remote control triggered by an arbiter (20),

- a camera (35) covering the entire playing field, - a processing station (14), making it possible to receive the signals from the remote control and the camera, to process the images and send the results for display,

-a display device of the results in the stadium.

The referee's remote control (20), the acquisition module for this remote control, the stadium signaling system and the associated interface module operate identical to that previously described, concerning the previous variant. The camera (35) is placed above the center of the terrain at a height allowing the acquisition of the entire terrain on the image (height of the order of 20 to 30 meters). The camera (35) is positioned using cables connected to the roofs of the stadium stands or to poles. A variant of the system consists in using several cameras, for example two cameras. In this case, each camera (35) is located above a goal and monitors the nearest camp (1/2 field).

The type of camera (35) has the following characteristics:

- variable lens aperture angle to adapt the area filmed on each stadium, - ability to distinguish players (1 to 11 and 21 to 31), even in difficult climatic conditions (rain ...)

The processing station (14) is composed of a module for acquiring the signal emitted by the remote control unit and of a computer which controls a specialized electronic card for image processing. This computer provides interface functions with the operator and with the stadium signaling system. The latter interface is not specified. The functions performed by the computer are described below:

* Memorization / digitization of the image On reception of the trigger top sent by the referee (20), the image received from the camera (35) is digitized and memorized. The image format is 512 x 512 pixels. The image covering a maximum length on the ground of the order of 120 cm, the precision of a pixel is of the order of 20 cm (120/512).

In the case where 2 cameras are used, 2 image processing modules are associated and Identical treatments are performed on the 2 digital images.

* Location of terrain lines in the image The camera (35) being suspended and therefore not completely fixed with respect to the terrain (wind, etc.), it is necessary to identify the boundaries of the terrain in the digital image.

2 devices are imagined: - either we identify the plot lines of the field in the image (touch lines, corners, and center lines),

- either we identify markers (colored spots) positioned along the ground: these spots have a diameter of lm (5 pixels) and are therefore easily identifiable.

From these benchmarks, we thus find the position of the lines of the terrain in the digital image. * Search for players (1 to 11 and 21 to 31) outside of the EU

The analyzes of the 2 halves of the field are carried out separately.

For each half of the field, the analysis is carried out by strips parallel to the corner line, starting with the strip adjoining it. This principle of analysis makes it possible to minimize the detection time for offside.

In each strip of land, the background color tasks are extracted by conventional image processing algorithms (convolution, hierarchical analysis ...).

Knowing the color of the jerseys of each team, the attacking team and the defending team, we identify to a team the color tasks detected. If among the first 2 color spots detected (closest to the corner line), we identify the color corresponding to the attacking side towards the goal of this field, then there is offside. In the case where the 2 color tasks closest to the corner line belong to the defending side, there is no offside.

In all cases, the result of this search is immediately sent to the stadium signaling system. in the case where 2 cameras are used, each image corresponds to half the terrain. These 2 halves are therefore treated, in fact, separately. - the treatments carried out make it possible to detect if there is an offside in the 2 halves of the field. The referee (20) obviously only takes into account the display corresponding to the half of the field on which the action takes place. * Positioning of all players.

After the signaling of any offsides, the image analysis continues until the entire field is completely processed (similar algorithms are used). This treatment makes it possible to position the 22 players (1 to 11 and 21 to 31) as well as the referee (20) on the field.

The positioning of all players (1 to 11 and 21 to 31) can be used: - either for an external display - or to check the consistency of the detection system and check for example the number of players (1 to 11 and 21 to 31 ) detected.

* Initialization Before the start of each half-time, an operator inserts into the station computer treatment (14) the side of each team and the color of the jerseys of each team and of each goalkeeper.

An analysis of an image, before kick-off of the match, confirms the correct detection of the colors of the jerseys of the 2 teams.

The present invention is described in the foregoing by way of nonlimiting example. It is understood that the skilled person will be able to produce various variants without departing from the scope of

1 invention.

Claims

1 - Method for detecting offside situations in the game of football, characterized in that one proceeds:

- detecting the position of each player (1 to 11 and 21 to 31) on the field;

- the issuance of a trigger signal at the time of judgment of the offside situation;

- comparing the position of the most advanced player on the attacking side with the positions of the two most distant players on the defending side; - to produce a signal in the event that said comparison is positive at the time of the emission of the trigger signal.

2 - A method of detecting offside situations in the game of football according to claim 1, characterized in that the emission of the trigger signal is carried out by manual action on the contactor of a portable unit comprising a transmitter.

3 - Method for detecting offside situations in the game of football according to any one of the preceding claims, characterized in that each of the players (1 to 11 and 21 to 31) on the field is equipped with an identifiable transmitter, the ^'ground being equipped with goniometric receivers connected to a computer realizing the operation signals for storing in real time the position of each player (1 through 11 and 21 to 31) equipped with a transmitter. 4 - Method for detecting offside situations in the game of football according to any one of claims 1 to 2, characterized in that one proceeds to the continuous acquisition of an image of the field by means of at least a camera, and that the video signal is processed to determine the positions of each of the players (1 to 11 and 21 to 31).

5 - Installation for the detection of offside situations in the game of football, characterized in that it consists of: a plurality of portable transmitters, each emitting a specific signal, carried by each of the players (l to 11 and 21 to 31 ); - at least one fixed goniometric receiver;

- a calculator for the real-time calculation of the position of each of the players (1 to 11 and 21 to 31) according to the signals generated by the goniometric receiver; - a portable transmitter comprising a means of initiating the phase of analysis of the offside situation;

a display means for displaying the result of the analysis.

6 - Installation for the detection of offside situations in the game of football, characterized in that it consists of:

- at least one camera (35) - a calculator for the real-time calculation of the position of each of the players (1 to 11 and 21 to 31) as a function of the signals generated by the goniometric receiver;

- a portable transmitter comprising a means of initiating the phase of analysis of the offside situation; a display means for displaying the result of the analysis.