Dozens of iPhones will be used to detect offside rule breaches in Soccer matches

The English Premier League is ditching its current system of video assist for referees in favor of a new one which uses dozens of iPhones to capture high frame-rate video from lots of different angles.

The system, pioneered by a US company known for its work in NBA baseball, will be used to detect breaches of soccer’s most controversial rule, known as the offside rule …

The offside rule

The offside rule says that a player cannot receive the ball from a fellow player while in the opposing side’s half of the field unless there are at least two defending players between them and the goal (this can include the goalkeeper).

The rule is intended to prevent a situation when players just hang out near the opposition’s goal, waiting for an opportunity to receive the ball. The idea is that the game is more exciting when it’s harder to get the ball into a position where a goal can be scored, though some take the view that more goals would be scored without the rule, and that’s what spectators want to see.

Offside is hard to accurately detect

One major criticism of the offside rule is that it’s almost impossible for the referee and other officials to accurately detect breaches, given that it often comes down to tiny distances, and things as fiddly as whether a player’s hand passed ahead of the position of an opposing player’s foot on the opposite side of the field.

To address this, a video assistance system has been used, which uses pixel-level measurements, but even so, claimed accuracy is still only 96%, and many complain that the time taken to review the results interrupts the flow of the game.

Enter dozens of iPhone 14s

A new system known as Dragon is now being introduced. This uses dozens of networked iPhone 14 models to capture the action from multiple angles, and uses AI to provide a rapid finding. The referee will still make the final call.

Wired reports.

Dragon, according to Genius, will initially use at least 28 iPhone cameras at every stadium in the Premier League […] The system uses the built-in cameras of iPhone 14 models and newer. The iPhones are housed in custom waterproof cases adorned with cooling fans and are connected to a power source. The team designed mounts that hold up to four iPhones clumped together.

Once the iPhones are positioned around the pitch, together they capture a constant stream of video from multiple angles […] This wealth of visuals apparently gives Dragon the ability to track between 7,000 and 10,000 points on each player at all times.

High frame-rate shooting is key, as the critical moment may fall between two frames when video is shot at 50fps. The iPhone system, in contrast, can capture up to 200fps. AI is used to ramp up the frame-rate when needed.

The system can auto-detect important impending events—such as a possible offside call—and scale up the frame rate of certain cameras temporarily, then scale back down when appropriate to save computing power.

Image: Genius Sports