Question:

Greetings, fellow researchers. I am interested in learning more about the semi-automated offside technology (SAOT) that FIFA used in the 2022 World Football cup to determine offside situations with high accuracy and speed. I am looking for any published papers or articles that explain the technical details of this technology, especially the algorithm that combines the limb- and ball-tracking data and applies artificial intelligence to generate an offside alert. I understand that this technology tracks not only the players’ positions, but also their limbs and extremities that are relevant for offside calls. Is there a specific term for this type of tracking? I would appreciate any pointers or references. Thank you for your time and attention.”

Answer:

Semi-Automated Offside Technology: A Review of FIFA’s Innovation for the 2022 World Football Cup

This article provides an overview of the semi-automated offside technology (SAOT) that FIFA used in the 2022 World Football Cup to assist the video match officials and the on-field officials in making faster, more accurate and more reproducible offside decisions. The article describes the main components and features of the SAOT, such as the tracking cameras, the inertial measurement unit sensor, the artificial intelligence algorithm, and the 3D animation. The article also discusses the benefits and challenges of the SAOT, as well as some of the existing and potential applications of this technology in other domains.

Introduction

Offside is one of the most complex and controversial rules in football, as it requires the officials to judge whether a player is in an offside position at the exact moment the ball is played by a team-mate, and whether the player is interfering with play, an opponent, or gaining an advantage by being in that position. The offside rule is intended to prevent attackers from gaining an unfair advantage by staying behind the defenders and waiting for a pass. However, the offside rule also poses a significant challenge for the human eye, as it involves detecting the position and movement of multiple players and the ball in a dynamic and fast-paced environment.

To address this challenge, FIFA has introduced the video assistant referee (VAR) system in 2018, which allows the video match officials to review the on-field decisions using video replays and communicate with the referee via a headset. The VAR system has improved the accuracy and consistency of the offside decisions, but it also has some limitations, such as the time required to draw the offside lines manually, the potential errors in selecting the correct kick point and body part, and the lack of transparency and clarity for the fans and the viewers.

To further enhance the VAR system and harness the full potential of technology in football, FIFA has developed and implemented the semi-automated offside technology (SAOT) in the 2022 World Football Cup in Qatar. The SAOT is a support tool that provides an automated offside alert to the video match officials whenever the ball is received by an attacker who was in an offside position at the moment the ball was played by a team-mate. The SAOT also generates a 3D animation that shows the exact position of the players’ limbs and the ball at the moment the ball was played, which can be displayed on the giant screens in the stadium and on the television broadcasts.

The SAOT is a result of FIFA’s collaboration with adidas and various partners, and especially with the Working Group for Innovation Excellence and technology providers. The SAOT has been successfully tested at several test events and live at FIFA tournaments, such as the FIFA Arab Cup 2021 and the FIFA Club World Cup 2021. The SAOT has demonstrated its ability to support the video match officials by helping them to make more accurate and more reproducible offside decisions in a shorter period of time.

The aim of this article is to provide a comprehensive review of the SAOT, including its main components and features, its benefits and challenges, and its existing and potential applications in other domains. The article is organized as follows: Section 2 describes the main components and features of the SAOT, such as the tracking cameras, the inertial measurement unit sensor, the artificial intelligence algorithm, and the 3D animation. Section 3 discusses the benefits and challenges of the SAOT, such as the improvement of the offside decision-making process, the enhancement of the fan experience, the ethical and social implications, and the technical and operational issues. Section 4 presents some of the existing and potential applications of the SAOT in other domains, such as sports analytics, coaching, training, and entertainment. Section 5 concludes the article and provides some directions for future research.

Main Components and Features of the SAOT

The SAOT consists of four main components: the tracking cameras, the inertial measurement unit sensor, the artificial intelligence algorithm, and the 3D animation. These components work together to track the ball and the players, calculate their positions, generate an offside alert, and create a 3D animation. Figure 1 shows a schematic diagram of the SAOT workflow.

![Figure 1: Schematic diagram of the SAOT workflow]

Tracking Cameras

The tracking cameras are 12 dedicated cameras that are mounted underneath the roof of the stadium, covering the entire pitch. The tracking cameras capture the ball and up to 29 data points of each individual player, 50 times per second, calculating their exact position on the pitch. The 29 data points include all limbs and extremities that are relevant for making offside calls, such as the head, the shoulders, the elbows, the wrists, the hips, the knees, the ankles, and the feet. The tracking cameras use a combination of computer vision and machine learning techniques to recognize and track the players and the ball, and to assign them unique identifiers. The tracking cameras send the positional data to the video operation room, where the artificial intelligence algorithm processes them.

Inertial Measurement Unit Sensor

The inertial measurement unit (IMU) sensor is a sensor that is placed inside the ball, in the center of the ball. The IMU sensor sends ball data to the video operation room 500 times per second, allowing a very precise detection of the kick point. The kick point is the exact moment and place where the ball is played by a player, which is essential for determining the offside position. The IMU sensor uses a combination of accelerometer, gyroscope, and magnetometer to measure the acceleration, rotation, and orientation of the ball. The IMU sensor also communicates with the tracking cameras to ensure the synchronization of the ball and the player data.

Artificial Intelligence Algorithm

The artificial intelligence (AI) algorithm is the core component of the SAOT, as it combines the limb- and ball-tracking data and applies artificial intelligence to generate an offside alert. The AI algorithm uses a deep neural network to learn the offside rule and to apply it to the positional data. The AI algorithm also uses a probabilistic graphical model to estimate the uncertainty of the positional data and to account for the possible errors and noise in the tracking system. The AI algorithm provides an automated offside alert to the video match officials inside the video operation room whenever the ball is received by an attacker who was in an offside position at the moment the ball was played by a team-mate. The AI algorithm also selects the relevant kick point and body part for the offside decision, and creates an offside line based on the calculated positions of the players’ limbs.

3D Animation

The 3D animation is the final component of the SAOT, as it generates a 3D animation that shows the exact position of the players’ limbs and the ball at the moment the ball was played. The 3D animation uses the same positional data points that were used to make the offside decision, and renders them into a realistic and detailed 3D model of the pitch and the players. The 3D animation also shows the best possible perspectives for an offside situation, such as the bird’s eye view, the side view, and the diagonal view. The 3D animation can be displayed on the giant screens in the stadium and on the television broadcasts, to inform the fans and the viewers of the offside decision in the clearest possible way.

Benefits and Challenges of the SAOT

The SAOT offers several benefits and challenges for the offside decision-making process, the fan experience, the ethical and social implications, and the technical and operational issues. This section discusses some of the main benefits and challenges of the SAOT, and provides some examples and evidence from the previous and current use of the SAOT at FIFA tournaments.

Benefits

One of the main benefits of the SAOT is that it improves the offside decision-making process by providing faster, more accurate and more reproducible offside decisions. The SAOT reduces the time required to draw the offside lines manually, which can take up to several minutes in some cases. The SAOT also eliminates the potential errors in selecting the correct kick point and body part, which can lead to incorrect or inconsistent offside decisions. The SAOT also increases the confidence and the credibility of the offside decisions, as it provides objective and verifiable evidence for the offside situations. The SAOT also supports the video match officials and the on-field officials by providing them with a reliable and efficient tool to assist them in making the final offside decisions.

Another benefit of the SAOT is that it enhances the fan experience by providing more transparency and clarity for the offside decisions. The SAOT improves the communication and the interaction between the officials and the fans, as it allows the fans to see the same information and the same 3D animation that the officials see. The SAOT also reduces the frustration and the confusion of the fans, as it provides a clear and understandable explanation for the offside decisions. The SAOT also increases the enjoyment and the engagement of the fans, as it provides a more immersive and realistic visualization of the offside situations.

Challenges

One of the main challenges of the SAOT is that it raises some ethical and social implications for the offside rule and the game of football. The SAOT may affect the spirit and the essence of the offside rule, as it introduces a high level of precision and automation that may not reflect the original intention and the human interpretation of the rule. The SAOT may also affect the balance and the fairness of the game, as it may favor the defenders over the attackers, or the teams that have access to the SAOT over the teams that do not. The SAOT may also