US-12616891-B2 - System and method for evaluating sport ball data

US12616891B2US 12616891 B2US12616891 B2US 12616891B2US-12616891-B2

Abstract

A system and a method related for evaluation of sport ball data. The method includes calibrating a first coordinate system of a first camera to a second coordinate system of a baseball field; capturing, with the first camera, one or more images including a first batter; determining biometric characteristics of the first batter based on the one or more images and the calibration of the first camera to the baseball field; mapping the biometric characteristics of the first batter to an upper positional limit and a lower positional limit of a first strike zone for the first batter; and determining positional limits of the first strike zone in the second coordinate system.

Inventors

Michael Ungstrup
Fredrik Tuxen

Assignees

TRACKMAN A/S

Dates

Publication Date: 20260505
Application Date: 20220803

Claims (20)

1 . A computer-implemented method for tracking pitched balls, comprising: storing, by a memory, a predefined relationship between limb lengths and strike zone limits; calibrating, by a processor, a first coordinate system of a first camera to a second coordinate system of a baseball field; capturing, with the first camera, one or more images including a first batter; determining, by the processor, biometric characteristics of the first batter including a first limb length based on the one or more images and the calibration of the first camera to the baseball field; mapping, by the processor, the biometric characteristics of the first batter to an upper positional limit and a lower positional limit of a first strike zone for the first batter based on the predefined relationship stored to the memory; determining, by the processor, positional limits of the first strike zone in the second coordinate system; tracking, by a tracking system comprising at least one of a radar or at least one camera, a flight of a pitched ball; and outputting, by the processor, a strike call or a ball call based on the flight of the pitched ball relative to the positional limits of the first strike zone, wherein the strike call or the ball call is output by an audio output device as an audible signal or by a display device.
2 . The method of claim 1 , further comprising: determining, by the processor, whether the flight of the ball includes a three-dimensional position where a portion the pitched ball is within the positional limits of the first strike zone in the second coordinate system.
3 . The method of claim 2 , further comprising: determining, by the processor, a three-dimensional trajectory of the ball, wherein, determining whether the flight of the pitched ball includes a three-dimensional position where a portion of the pitched ball is within the positional limits of the first strike zone in the second coordinate system includes determining whether the trajectory of the pitched ball includes a three-dimensional position where a portion the pitched ball is within one radius of the pitched ball of the positional limits of the first strike zone in the second coordinate system.
4 . The method of claim 2 , further comprising: outputting, by the processor, the strike call when the flight of the pitched ball includes the three-dimensional position where the pitched ball is within the positional limits of the first strike zone in the second coordinate system; and outputting, by the processor, the ball call when the flight of the pitched ball does not include a three-dimensional position where the pitched ball is within the positional limits of the first strike zone in the second coordinate system.
5 . The method according to claim 1 , wherein the tracking system includes a radar device and a second camera mounted in a high home position.
6 . The method according to claim 5 , wherein the first and second cameras and the radar device are time synced to one another, further comprising: identifying, by the processor, a time of a key moment relating to the pitched ball based on data from the radar device; and selecting, by the processor, an image from one of the first and second cameras corresponding to the time of the key moment for mapping the biometric characteristics of the first batter to the upper positional limit and the lower positional limit of the first strike zone.
7 . The method of claim 2 , wherein it is determined, by the processor, that the flight of the pitched ball includes a three-dimensional position where a portion of the pitched ball is within the positional limits of the first strike zone in the second coordinate system when any one of the three-dimensional positions of the pitched ball is no further than one radius of the pitched ball from the positional limits of the first strike zone in the second coordinate system.
8 . The method of claim 1 , wherein the biometric characteristics of the first batter are mapped, by the processor, to the upper positional limit and the lower positional limit of the first strike zone based on a first identified anatomical feature of the first batter corresponding to the lower positional limit of the first strike zone.
9 . The method of claim 8 , wherein the biometric characteristics of the first batter are mapped, by the processor, to the upper positional limit of the first strike zone based on a predetermined height added to a height of a second identified anatomical feature of the first batter.
10 . The method of claim 8 , wherein the upper positional limit of the first strike zone is determined, by the processor, by adding a predetermined height to a height of the first identified anatomical feature of the first batter.
11 . The method of claim 10 , wherein the predetermined height is based on the biometric characteristics of the first batter.
12 . The method of claim 1 , wherein the positional limits of the first strike zone are determined, by the processor, in the second coordinate system based on a plane corresponding to a width of a home plate in a vertical plane perpendicular to a line from a center of a pitching rubber to a center of the home plate.
13 . The method of claim 1 , wherein the predefined relationship between the limb length and strike zone limits is determined from observations of actual strike zone upper and lower limits determined based on analyses of a number of players with known biometrical characteristics as the players assume batting stances.
14 . The method of claim 1 , wherein the strike call or the ball call is output to provide to a human decision maker an indication of a system-determined decision of the strike call or the ball call.
15 . The method of claim 1 , wherein the strike call or the ball call is output to provide an official system-determined decision of the strike call or the ball call that is able to be overruled by a human decision maker.
16 . A system for tracking pitched balls, comprising: a memory storing a predefined relationship between limb lengths and strike zone limits; a tracking system comprising at least one of a radar or at least one camera configured to track flights of pitched balls; a first camera capturing images of batters; and a processor configured to perform operations comprising: calibrating a first coordinate system of a first camera to a second coordinate system of a baseball field; receiving, from the first camera, one or more images including a first batter; determining biometric characteristics of the first batter including a first limb length based on the one or more images and the calibration of the first camera to the baseball field; mapping the biometric characteristics of the first batter to an upper positional limit and a lower positional limit of a first strike zone for the first batter based on the predefined relationship stored to the memory; determining positional limits of the first strike zone in the second coordinate system; receiving, from the tracking system, tracking data for a flight of a pitched ball; and outputting a strike call or a ball call based on the flight of the pitched ball relative to the positional limits of the first strike zone, wherein the system further comprises at least one output device for outputting the strike call or the ball call, the at least one output device comprising: an audio output device outputting an audible signal; or a display device.
17 . The system of claim 16 , wherein the processor is configured to perform further operations comprising: determining whether the flight of the ball includes a three-dimensional position where a portion of the pitched ball is within the positional limits of the first strike zone in the second coordinate system.
18 . The system of claim 17 , wherein the processor is configured to perform further operations comprising: determining a three-dimensional trajectory of the ball, wherein, determining whether the flight of the pitched ball includes a three-dimensional position where a portion of the pitched ball is within the positional limits of the first strike zone in the second coordinate system includes determining whether the trajectory of the pitched ball includes a three-dimensional position where a portion the pitched ball is within one radius of the pitched ball of the positional limits of the first strike zone in the second coordinate system.
19 . The system of claim 17 , wherein the processor is configured to perform further operations comprising: outputting the strike call when the flight of the pitched ball includes the three-dimensional position where the pitched ball is within the positional limits of the first strike zone in the second coordinate system; and outputting the ball call when the flight of the pitched ball does not include a three-dimensional position where the pitched ball is within the positional limits of the first strike zone in the second coordinate system.
20 . The system of claim 16 , wherein the tracking system includes the radar device and a second camera mounted in a high home position.

Description

PRIORITY CLAIM The present disclosure claims priority to U.S. Provisional Patent Application Ser. No. 63/203,927 filed Aug. 4, 2021; the disclosure of which is incorporated herewith by reference. BACKGROUND Calling strikes and balls and the making of other judgment calls as well as the application of rules to observed actions is an integral and important part of the game of baseball. Strikes and balls are called by the home plate umpire after every pitch has passed the batter unless the batter makes contact with the baseball (in which case the pitch is automatically a strike). Of course, determining whether the batter has made contact with the pitched ball is one more judgment call that is currently decided by the umpire. Under the current rules of Major League Baseball, the official strike zone is the area over home plate from the midpoint between the batter's shoulders and the top of the uniform pants to a point just below the kneecap of the batter. By rule, the strike zone is determined when the batter is positioned in the batter's stance and prepared to swing at a pitched ball. Thus, a first batter's strike zone is typically different from a second batter's strike zone, and the strike zone for a given batter may change between or during at-bats and between ball games. Systems measuring baseball flight and evaluating pitches during a game have existed and received much attention for years. One exemplary system employs a Multi-Frequency Continuous Wave (MFCW) X-band Doppler radar. Radar waves transmitted from the radar and reflected by the baseball in flight generate an observable Doppler shift when received by the radar. This shift is proportional to the radial velocity of the baseball in relation to the radar. The radar measures the direction from the radar to the ball by employing multiple receiving antennas and observing phase differences associated with the signals received at these receivers. By employing multiple frequencies, the range to the ball can also be determined. For tracking pitches, a so called “high-home” location is a particularly advantageous placement of the radar from which to make measurements of radial velocity as the signal strength of reflected waves is consistently high. The “high-home” location places the radar in a position elevated above the pitcher's rubber and home plate and behind home plate—preferably with the radar securely mounted to existing structures such as a fence or the stands. This position is generally selected to gain as clear a view of home plate as possible while minimizing obstruction from the batter, the catcher and the umpire. In another example, a camera-based system may employ cameras with a high frame rate (e.g., 60 Hz or higher), high resolution (e.g., HD, 4K, or even higher) and a field-of-view covering the area over which a pitch is likely to be thrown (e.g., including the pitcher's rubber, home plate and the batter's box, the area therebetween and an immediately surrounding area). The ball's position in an image plane may be detected when the ball is in the field of view of the camera. The position of the ball may, for example, be defined by a vector in space from the focal point of the camera to the 3D position of the ball. Detecting the ball using multiple cameras simultaneously allows the 3D position of the baseball to be determined by combining these vectors (e.g., via triangulation in known stereo vision techniques). In still another example, a system can include both a radar and one or more cameras, where the observations from both types of sensors are combined to determine a path of flight of a ball. Regardless of the type of system used, it is advantageous to synchronize the sensor input or to otherwise timestamp observations and employ sensor fusion across modalities. SUMMARY The present disclosure relates to a method which includes calibrating a first coordinate system of a first camera to a second coordinate system of a baseball field; capturing, with the first camera, one or more images including a first batter; determining biometric characteristics of the first batter based on the one or more images and the calibration of the first camera to the baseball field; mapping the biometric characteristics of the first batter to an upper positional limit and a lower positional limit of a first strike zone for the first batter; and determining positional limits of the first strike zone in the second coordinate system. In an embodiment, the method further includes tracking a flight of a pitched ball; and determining whether the flight of the ball includes a three-dimensional position where a portion the pitched ball is within the positional limits of the first strike zone in the second coordinate system. In an embodiment, the method further includes determining a three-dimensional trajectory of the ball, wherein, determining whether the flight of the pitched ball includes a three-dimensional position where a portion of the pitched ball is within