Emirates Stadium's camera

SportsTech: Football

Software is changing the way that football coaches prepare their match tactics

Gone are the days of Premier League coaches scribbling formations and tactics on blackboards. These days players are more likely to be studying iPads during team briefings or breaks in play. All this has been made possible by football analysis software developed over recent years.

Analysing the team and individual performances as well as scouting the opposition has become the art of computer analysts who channel a flood of data into pools of visual information for managers and individual players to assess. Anyone who has played the top selling Football Manager will be familiar with the 2D images and views it displays. Now those views and statistics are available from real matches – recorded, coded and analysed within 24 hours of the game finishing.

Leading the digital coaching revolution for football is Leeds-based company Prozone, which has been developing its systems since 1998. There are two Prozone systems used by football coaches for analysing performance. The majority of top clubs will use the Prozone 3 system. In this configuration eight to 12 cameras are installed in the stadium, usually hanging from the roofs of the stands, allowing anything that takes place on the pitch at any given point in the game to be captured.

"This allows us to track all the players throughout the game and provide not only the technical, but also all the off-the-ball movement, that can provide physical data to clubs," Will Jones, performance analyst at Prozone Sports explains. "It can also provide a 2D tracking system, similar to what they have on computer games where you are the football manager, when you see an animation of the players running around."

A cut-down system can be seen at clubs in the lower leagues. The Matchviewer system works off just a single camera – perhaps the TV camera or the football club's own footage from the gantry. Such footage tends to follow the ball, allowing the same technical on-the-ball statistics. Obviously, with the one-camera system anything outside the camera shot cannot be seen or any off-the-ball movement or player tracking cannot be incorporated.

Camera set-up

With the minimum eight-camera Prozone system there are two groups of three cameras at alternate corner flags and then one camera in the remaining opposite corners. "It is the system that we always try to use as each camera is fixed and looks at a certain area of the pitch," Jones says. "It means that we try to have each area of the pitch covered by multiple cameras, which allows for a back-up in case one of them goes down, but also means that when we go through the process of coding the games the different camera angles allows us greater flexibility and precision.

"Having multiple cameras and multiple views in a game of football where there are 22 players in a very small area, all crossing over is very beneficial."

The benefit of more than eight cameras is mainly a solution for a stadium where the normal set-up can't be incorporated. "It is just to guarantee that in different set-up positions we still have every area of the pitch covered and it is as similar to the eight-camera set-up as possible," Jones explains. "Sometimes there are a few cameras there for back-up purposes in case something was to go wrong with one or two of the cameras, or if there was an obstruction of the view. The cameras themselves are all specific Sony HD cameras encased in small plastic domes to protect them from the elements. To most casual observers they are indistinguishable from the CCTV security cameras dotted around modern grounds.

Recording the footage is only the first part of the process, it then has to be captured, coded and delivered to the coaches to manipulate. All the cameras will be connected up to the server. "In general there is a certain order to the match-day operation," Jones says. "It a case of checking the cameras prior to the game; they are turned on and connected up to the server around half an hour before kick-off. Then when the game kicks off, the outside broadcast feeds will start.

"As well as all our cameras we will also use the TV footage or club cameraman as this is one that always effectively follows the ball, so we really get to draw from nine cameras. These are all hooked up to one server and uploaded and at the end of the game the footage can be downloaded from there, and used to undertake the tracking process."

Manual coding

The footage can be remotely collected from the Prozone office in Leeds and coding can begin. The coding and tracking is, perhaps surprisingly, a manual process. At present no software is able to follow the players automatically or know exactly what each one is doing in the game. "The software we do have still has a level of intelligence where we only have to input a minimal amount for it to produce the final information, but it is still a manual process.

"We have a large department dedicated to the processing the games. Once the footage is obtained it will be sent to the team responsible for that match. They then have to go through the whole game, with potentially up to nine camera angles, and they will be coding on-the-ball events as well as tracking players. They literally go through it frame by frame with access to multiple camera angles and using the coordinates and pitch dimensions."

Each of the 20 English Premier League pitches vary in size – from Manchester City's Etihad Stadium, which is 116.5 × 78 yards (106 × 71m), to the West Ham United's Upton Park, which is 110 × 70 yards (100 × 64m). To allow the coding to be accurate each pitch dimension is incorporated into the system.

"Once that is calibrated and the guys are marking down where on the pitch these events are happening and where players are moving, then from that the system can work out the distance a player has covered and therefore his speed and direction," Jones explains.

In terms of the actual coding there are 60-65 different events that can be input into the program, for example a pass, a tackle or a shot. From the logging of these events the systems can derive that next move that must come out of one of 250 events.

"For example, if I was coding a match I could say 'Player X passes the ball' and the next event might be 'Player Y touches the ball in the penalty area and has a shot'," Jones says. "I would mark 'Player X' on the pitch, select him and put 'Pass'. Next I would mark 'Player Y' on the pitch, select him and put 'Touch' and then mark his position again and put 'Shot'.

"What the system could then work out is the direction of the pass, the length of the pass, that it is a penalty area entry or it could work out it was a successful pass. It also means that you can't input errors. For example if you input that the ball has gone out of play it will work out the next event must be a corner kick, goal kick or throw-in and it wouldn't let you input anything else.

The whole system has a number of rules to allow for accuracy and to make the actual coding process a lot easier. You don't have to input all the multiple derived events, but you can input the basic ones and the system will work the rest out for you based on the marking on the pitch, on the positions and the sequence of events."

All the coding is carried out by Prozone. The data is then delivered to the clubs, utilising software provided by Prozone, and the analyst at the football club can extract the information required.

"The idea of the end product that the user receives is a very, very interactive piece of computer software," Jones says. "So it is very easy to use and very easy to train people up on how to use it. It is more about how people use the software and what they do with it where people start to establish themselves as good analysts.

"The software that they receive allows you to flick between the different learning tools. There is a simple video in there in case you simply want to show a certain thing, then in Prozone 3 there is the 2D animation as well so you could play those side-by-side. You could show something in the video footage and then replay to show something else outside of that camera angle, for example you could show off-the-ball runs that the player with the ball may have missed.

"You can flick into pure numbers and bring up tables and grids of all the different statistics that have been calculated and then that can be represented more visually by bringing up graphs and charts.

"Also there is a whole section within the software where all those numbers and statistics are taken and shown visually on the football pitch. For example, you could look at how many passes have been made, say 300, as just a figure or you could flick into the analysis section of the software where you can see all 300 of those passes as arrows, and can visually see the distance and direction of those passes."

Individual players can click on their name and see everything they have done. Goodbye to the traditional CDs and VHS cassettes, football is now in the tablet age.

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