Method and system for determining whether a spherical element impacts with a component of a playing field, or arranged on or proximate thereto

Abstract

A method and system for determining whether a spherical element impacts with a component of a playing field, or arranged on or proximate thereto. The method includes acquiring images of a surveillance area of a field that covers at least part of said component, such as a delimiting perimeter line of a game area or a target, performing an approximate detection of an impact of a spherical element relative to that component or proximate thereto, with an object detection and recognition system that can discern when the detected object is indeed a spherical element, automatically selecting one of the images acquired for the same point in time and that includes the area where said impact has occurred, and analyzing the selected image to check if the spherical element has impacted or not with the component.

Claims

1. A method for determining whether a spherical element impacts with a playing field, or with a component arranged on said playing field or proximate to said playing field, said component comprising one of a physical structure, physical marking, or virtual marking, and said playing field being made up of game areas, where the method comprises the steps of: a) acquiring, with detection devices comprising at least a plurality of high speed cameras, a sequence of images of at least one area of surveillance of said playing field covering at least part of at least said component and storing the sequence of images on a memory; b) performing, by a processor of a computer system operatively connected with said detection devices, when the detected object is indeed a spherical element, an approximate detection of the impact of the spherical element with said component or proximate thereto; c) automatically selecting, by the processor in response to said approximate detection, at least one image, from said sequence of images, acquired for a point in time that includes the at least one area of surveillance of the playing field where a bounce takes place and when the bounce takes place; and d) determining, with the processor, that the spherical element has impacted with said component; wherein: prior to said approximate detection of the impact of step b), a pre-detection of the passage of the spherical element through at least two points located at different heights is performed with at least the detection devices, and based on said pre-detection, a prediction of the trajectory to be followed by the spherical element towards the ground and a predetermination or predefinition of an approximate area where the impact or bounce will occur is performed by the processor, said pre-detection being performed using at least two detection devices.

2. The method according to claim 1, wherein said detection and said pre-detection of the impact are done by the same plurality of high speed cameras.

3. The method according to claim 1, wherein said detection means further include sound detection devices which are operatively connected to said processor.

4. The method according to claim 3 wherein said prediction of the passage of the spherical element through at least two points located at different heights is further performed with the assistance of a three-dimensional type object detection and recognition system including at least scanners located at different heights.

5. The method according to claim 3, wherein the scanners are laser scanners, and the three dimensional type object detection and recognition system further comprises ultrasound devices, and the method comprises performing said automatic discerning using said laser scanners to obtain distance information, with respect to said laser scanners, from each point of contact of the laser beams emitted by the laser scanners with the detected object, and based on said distance information obtained for a group of contact points.

6. The method according to claim 1 wherein in said step a) said acquisition of images only covers several targets within the area of surveillance of said playing field.

7. The method according to claim 1, wherein said approximate detection of step b) comprises performing at least two detections that include at least a moment when said impact or bounce happens and/or at least a moment immediately before the impact or bounce and/or at least a moment immediately after the impact or bounce, using in said step c), as the time point for the automatic selection of said at least one image, at least one of the time points of said at least two detections.

8. The method according to claim 1, wherein said step d) comprises showing said at least one selected image on displaying means to allow performing the aforementioned analysis by visually judging the image, or to supplement said analysis.

9. The method according to claim 1, wherein: said step c) comprises selecting a plurality of images from said sequence of images and arranged in sequence, wherein the plurality of selected images includes the at least one image acquired for the point in time of the approximate detection and images for points in time before and after that point; and said step d) comprises a video playback including said plurality of images, in slow motion forward and/or backwards and/or stopping in order to perform the aforementioned visual judgment.

10. The method according to claim 1, comprising performing said step a) the plurality of high speed cameras covering the various components of the playing field, or arranged on or proximate thereto, from different sides thereof, and/or the different sections of the perimeter lines from both sides and/or ends thereof and/or all the targets from different sides thereof.

11. The method according to claim 1, comprising using said predefinition of said approximate area where the bounce will occur to activate and/or control one or more high-speed cameras whose coverage area includes the approximate predefined area.

12. The method according to claim 1, comprising automatically discerning when the detected object is indeed a spherical element based on the difference in the detection signals caused by being detected by the detection and recognition system in comparison with the detection signals resulting from the detection of other elements, stationary or mobile, of at least different shape and size.

13. The method according to claim 1, wherein said spherical element is a tennis ball and said playing field is a tennis court, with said game areas being the different rectangular areas of said tennis court.

14. The method according to claim 1, wherein said spherical element is a tennis ball and said playing field is a tennis court, with said game areas being the different rectangular areas of said tennis court and wherein the method comprises selecting as perimeter lines on which check when the tennis ball has really bounced or not, the following: those demarcating a respective service area to which a player will serve or has served, to judge whether the tennis ball bounces in or out of the service area; or those demarcating the total game area for a single or a doubles match during the rally after the service.

15. The method according to claim 14, comprising receiving information on whether, after the service, the tennis ball has touched a net or not of the playing field, and based on this information, after judging whether the tennis ball bounces in or out of the service area, the method comprises issuing a signal indicating that: the serve must be repeated, when the ball has bounced inside the service area but after touching the net, or the serve must not be repeated, when the ball has bounced outside the service area after touching the net.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The aforementioned and other advantages and characteristics will be understood more fully from the following detailed descriptions of embodiments with reference to the accompanying drawings, to be taken by way of illustration and no limitation, in which:

(2) FIG. 1 is a schematic representation in ground plan view of the system proposed by the second aspect of the invention with its elements arranged on a tennis court, and associated with the detection of the bounce of a tennis ball on perimeter lines delimiting the game areas;

(3) FIG. 2 is a schematic representation in elevation view of detection devices of the detection and recognition system proposed by the second aspect of the invention, arranged at different heights relative to a perimeter line of a game area;

(4) FIG. 3 is an analogous view to FIG. 1, but associated with the detection of the bound of a tennis ball on targets placed in different areas of the tennis court, and represented by dashed lines.

DETAILED DESCRIPTION OF AN EMBODIMENT

(5) FIG. 1 illustrates a tennis court with a series of rectangular game areas Z1-Z10 into which the court is divided, for use during a tennis match, whereby the rectangular areas Z1-Z10 are delimited by perimeter lines L, which both define the total game area, which for a singles match does not include areas Z7, Z8, Z9 and Z10 but which in doubles matches are included, as the sub-areas of game, such is the case of areas Z2, Z3, Z4 and Z5, corresponding to the service areas, it being of interest to detect if the tennis ball bounces both on the perimeter lines L of said service areas Z2-Z5 L lines, during the serve, and on the lines which delimit the total game area, during the rally after the service.

(6) The system proposed by the second aspect of the invention includes, for the embodiment illustrated by said FIG. 1: image acquisition and registration means that include a plurality of high speed cameras C, arranged around the tennis court, preferably at ground level, covering different portions of perimeter lines L and areas adjacent thereto; means of detection configured and arranged to make an approximate detection of a bounce of the tennis ball B on one of the perimeter lines L or proximate thereto, and that comprise a system of detection and recognition of objects that allows to discern when the detected object is indeed a tennis ball, and which includes a series of laser scanners or groupings of laser scanners S, which together cover all the perimeter lines L; automatic selection means, which in the illustrated embodiment are implemented in the electronic system SE, in connection with the detection means, with access to the recorded images, and configured to automatically select, in response to the approximate detection, one or more of the recorded images, including the image corresponding to the point in time associated with the approximate detection and which includes the area where the bounce has occurred; means of displaying V to show the selected image to allow it to be judged by visual analysis; and means of analysis, which in the illustrated embodiment are implemented in the electronic system SE, and which are configured to automatically analyse the selected image.

(7) It should be understood that the cameras C are represented schematically for greater clarity. In fact, in particular as regards the cameras C arranged on either side of the centre net N, adjacent thereto, these do not overlap a portion of the lines L such as could be understood by the schematic representation thereof, but instead they are of a size and/or are arranged so that their coverage area also includes the portions of the perimeter line immediately adjacent to the respective side of the centre net N.

(8) Alternatively the arrangement of the cameras adjacent to the net N can be dispensed with, and instead one or cameras C arranged to one side of the court, but at a distance from the net N, can be used, whose angle of vision allows images to be captured that are behind the net N (through, for example, a translucent portion thereof), in particular images of the perimeter lines L of the other side of the court.

(9) According to one preferred embodiment, one or preferably each of the rectangles C do not represent only one camera but instead various cameras, for example four, stacked one over the other and with different angles of vision to cover different sections of the same perimeter line L.

(10) As regards the scanners S, these are preferably arranged at different heights in order to detect different kinds of objects, including some at a height considered suitable for detecting the players.

(11) The schematic representation of FIG. 1 does not show the connections existing between the different means of the system proposed by the second aspect of the invention, either because these are wireless or in order to provide a greater clarity in the illustration. It should be understood that any type of connection between those means is possible.

(12) Also, although FIG. 1 only schematically represents an electronic system SE, for other embodiments, not illustrated, the system of the second aspect of the invention comprises the inclusion of one or more electronic systems corresponding to one or more of the aforementioned image recording, selection and analysis means, as well as the control means for the laser scanners L and cameras C.

(13) FIG. 1 also shows a screen as a displaying means V, which displays a scene where the tennis ball B appears deformed when bouncing on a peripheral line L is shown, where said image, if it corresponds to the maximum deformation of the ball B, will be the image that will be automatically analysed and/or shown to the player or umpire on said screen V for its visual inspection.

(14) For a preferred embodiment, each of the elements shown with the reference S in FIG. 1, includes three laser scanners, as illustrated in FIG. 2, one of them S1 arranged at ground level (or very close to it), or first level, and the other two S2, S3 arranged at a certain height from the first scanner, or second level, approximately at 80 cm for scanner S2 and 90 cm for scanner S3 (although these heights may be others for other embodiments).

(15) FIG. 2 illustrates the trajectory followed by a tennis ball B until in bounces (moving according to arrow D1) on one of the perimeter lines L, and from when it bounces (moving according to arrow D2) thereon, the ball being illustrated with a solid line at the time of the bounce and with dashed line for the rest of its trajectories towards and from the bounce.

(16) Continuing with the description of FIG. 2, during the trajectory of the ball B towards the bounce, this is first detected by the laser scanner S3 and immediately after by S2, considering such consecutive detections as representing the passage of a moving object, which the detection and recognition system identifies as tennis ball (as explained in a previous section). These scanners S2 and S3 operate, according to one embodiment, at a scan speed of 100 MHz, and allow the predefinition of a first approximate area or pre-area where the ball B will fall, with dimensions, in ground plan view, in the order of around 50 cm.

(17) Following trajectory D1, the tennis ball B finally enters the coverage area of the scanner S1, which, according to one embodiment, operates at about 50 MHz, which, taking into account the average speed at which the ball B tends to travel, enables S1 to perform around two or three detections thereof (the aforementioned approximate detection), at the moment of the bounce and/or just before and/or just after it, within an approximate area of 15 cm at most, that, while it is relatively small cannot assure whether or not the bounce occurred on the perimeter line L, and therefore this approximate detection is used, as already explained above, to select the image or images captured by the cameras for the same point or points in time.

(18) As explained in a previous section, the aforementioned predefinition of the area in which the ball B will bounce can be used to select and, if necessary, activate the camera best positioned to cover this area, and therefore to perform the mechanical micro-focus thereof if required to ensure greater accuracy and speed in the final answer, i.e. in the result of the analysis of whether the ball B has bounced inside or outside the game area.

(19) All these actions happen in milliseconds and time is crucial to activate the camera and mechanically focus on the area of the bounce, if necessary, and therefore, to be able to perform the analysis of the chosen image almost in real-time with high definition without using mega-cameras, i.e. the very expensive cameras of the Hawkeye system.

(20) The scanner S1, in its various detection points, before the bounce, during the bounce and right after, provides the approximate area of the bounce in a much more accurate manner than the area predefined by S2 and S3, but above all it gives information about the moment of the bounce and the adjacent moments that allow the system and its choice to be optimised to be able to work with almost in real-time with the information from the selected high speed camera, thus achieving, thanks to the mechanical focus, maximum errors of half a millimeter compared with the 3 millimeters of the Hawkeye system.

(21) FIG. 3 shows the system proposed by the second aspect of the invention, incorporating the same elements as the system illustrated by FIG. 1, but applied to the detection of the bounce of the tennis ball B on some targets A1-A8 distributed throughout the court, within the game areas, in particular they have been illustrated within areas Z1 to Z6, or even within two areas, as is the case of the target A4 with respect to areas Z4 and Z6. Obviously, the illustration is schematic only, and a single movable target may be used from different positions.

(22) According to one embodiment, targets A1-A8 will not be visible on the tennis court itself, but they will be virtual targets (or a single movable target occupying the different positions illustrated) visible on a screen that shows them in relation to the tennis court, i.e. to show, for example, a tennis court with the targets as shown in FIG. 3, or a part thereof (for example those placed on the side on which the player should aim the ball).

(23) Also, although FIG. 1 only schematically represents an electronic system SE, for other embodiments, not illustrated, the system of the second aspect of the invention comprises the inclusion in one or more electronic systems of one or more of the aforementioned image recording, selection and analysis means, as well as of control means for the laser scanners L and cameras C.

(24) FIG. 3 also shows the electronic system SE and a screen as a displaying means V, which displays a scene where the tennis ball B appears deformed when bouncing on one of the targets, specifically on target A1, which will be the image that will be automatically analysed and/or shown to the player or umpire on said screen V for its visual inspection.

(25) The embodiments described with reference to FIG. 1 are also valid to describe analogous embodiments with reference to FIG. 3, simply by changing the component on which the bounce of the ball B occurs, that in FIG. 1 is the perimeter line L and in FIG. 3 is the target A1-A8 (obviously the same can be said for another kind of component than are not either the perimeter lines L or the targets A1-A8).

(26) A person skilled in the art could introduce changes and modifications in the described embodiments without departing from the scope of the invention as defined in the attached claims.