- What is a Tennis Line-Calling System?
- Best Tennis Line-Calling Systems
- 3. BaselineVision
- 4. FoxTenn
- 5. Wingfield
- 6. In/Out
What is a Tennis Line-Calling System?
A line-calling system, also known as an electronic line-calling system,m is a technology used in tennis to make accurate and reliable line calls during matches. The line-calling system utilizes a combination of cameras, computers, algorithms, and microphones to track and calculate the trajectory of the ball. With the help of these technologies, the line-calling system can determine whether the ball landed inside or outside of the court.
Best Tennis Line-Calling Systems
Here is a list of the best line-calling systems and their features. These systems are not in any particular order.
1. Hawk-Eye
Hawk-Eye is a UK-based computer vision system that is used in numerous sports, most famously in tennis. Hawk-Eye is intended to visually track the tennis ball’s trajectory and calculate statistically its most likely path as a moving image.
In simple terms, Hawk-Eye forms a very advanced estimate of the ball landing spot and displays it as a video. This result is called a Shot Spot.
How Hawk-Eye Works
Hawk-Eye systems work by using a principle called triangulation with visual images. They gather data from multiple high-speed video cameras which are placed at various spots and angles around the playing area. During a tennis match, there are usually 10 Hawk-Eye cameras in action.
In every frame taken by each camera, the Hawk-Eye system deduces which pixels in the image represent the ball. Then, it locates the ball by comparing its position with at least two different physical cameras that are set up in different positions and angles. A series of these frames form a record of the ball’s path. By using these records, the system can predict the future flight path of the ball and where it will interact with any of the playing area’s borders or objects that are programmed into the database.
The end product of Hawk-Eye is a graphic image of the ball’s trajectory and playing area, which can be provided to match officials, television viewers, and coaching staff in almost real time.
Hawk-Eye summarised
Hawk-Eye is the most popular and accurate line-calling system in the world. it is officially used in the ATP and WTA. Hawk-Eye is intended for top-tier professional tennis and it doesn’t have features for regular tennis players.
2. Zenniz
Zenniz is a Finland-based ITF-approved smart tennis court system that is available in the USA and Europe. It offers a comprehensive system that includes:
- Smart net post with:
- 2x large LED panels on both sides to display real-time performance feedback
- 2x integrated high-resolution cameras
- 1x integrated touch screen.
- 30x audio sensors (microphones)
- 2x baseline cameras for recording and streaming gameplay
- Mobile app for players
- Mobile app for umpires
- Web dashboard for tournament organizers
Key Features
Automatic line calls
Zenniz measuring unit has a built-in high visibility screen that shows the player whether the ball was in or out. Zenniz uses a unique patented Dual Tracking technology that uses both visual and auditory data to deduce the trajectory of the ball. In unclear situations, each shot can be reviewed on the on-court screen.
Statistics & Insights
Zenniz has a mobile application that works in cooperation with the on-court measuring unit. The player can create a Zenniz profile and link it to an on-court Zenniz measuring unit. While the player plays the Zenniz measuring unit follows the game and collects data from players’ movements and shots creating statistics and insights.
Video Highlights
The Zenniz measuring system includes a baseline camera that can be set to record the player’s matches. The baseline camera can also be used to stream official matches.
Interactive player drills
One of the most innovative features of Zenniz is interactive drills. The Zenniz measuring unit has a built-in high-quality camera that can identify the player and measure his/her shots. With the help of Zenniz’s interactive measuring unit, the player can engage in various drills such as accuracy drills, and receive feedback on his/her performance.
How Zenniz Works
Zenniz line calls use patented Dual Tracking technology, which uses visual and auditory data to calculate the ball’s trajectory.
The first element of the Dual Tracking system is a patented audio triangulation system designed to locate the sound source using the distances between the microphones and the sound source. The Zenniz sound triangulation system consists of 30 sound sensors (microphones) mounted around the court.
The function of the sound sensors is to analyze the sound waves generated by the impact of the ball and the movement of the players. The function of the sound sensors is to analyze the sound waves generated by the impact of the ball and the movement of the players.
Through the sound sensors, Zenniz can create a real-time map of the court.
The second part of Dual Tracking is camera tracking, which consists of four high-resolution cameras. These cameras are positioned around the court so that there is one camera on each side of the court behind the back line and two cameras next to the net pole in the Zenniz measuring device.
The cameras work in harmony with each other and capture every movement of the ball and the players.
By combining audio triangulation and camera tracking, Zenniz can operate with excellent accuracy, creating a digital picture of the court, ball movements, and player position. In addition to line calls, Zenniz can provide players with advanced detailed statistics to help them better understand their own game.
So Zenniz is not only a line-calling system but also a personal coaching platform for the player.
Zenniz summarised
Zennis is a versatile, accurate, and affordable tennis line-calling system. Its technology is based on a combination of audio triangulation and camera tracking. Zennis can be used for both competitive tennis and regular practice.
Compared to other line scoring systems, Zenniz also offers many interesting features for ordinary tennis players, such as practice sessions. Through these practice sessions, players can develop their skills independently and get feedback on their performance.
3. BaselineVision
Baseline Vision is an ITF-approved portable line-calling device. It is available worldwide with free shipping and a 30-day free trial. The system includes two main components: the device and a smartphone application.
- The device:
- 2x Full HD cameras (one on each side) recording at 60 frames per second
- 2x LED panels (one on each side) that signal line calls with colors
- 2x speakers (one on each side) for audio line call notifications
- Power button located on the top
- Built-in spirit level to ensure proper camera alignment
- Detachable battery for easy replacement
- LAN port for wired connectivity
- USB port for data transfer
- Power port for battery charging
- Charging cable included
- Carrying case and strap included
- Mobile app for players
- Line calls
- Games
- Statistics
Key Features
Automatic line calls and Challenges
The Baseline unit features two built-in LED lights and two speakers that signal line calls. These calls are determined by an AI processor, which analyzes live footage to calculate key shot properties such as speed, trajectory, and player positioning.
Statistics
The Baseline App monitors your on-court performance by tracking shot speed, ball placement, player positioning, and fitness metrics. This data is designed to help players assess their progress and improve their game.
Video Replays
With video replays, players can review their latest drill and analyze their technique and movement in greater detail.
Gamified Drills
Currently, the Baseline app features two games: Deeper and 2 Minute Challenge. In Deeper, the farther your shot lands, the more points you earn. The 2 Minute Challenge, as the name suggests, gives you two minutes to hit as many shots as possible in a rally.
How BaselineVision works?
The detailed system behind the Baseline unit is not fully disclosed. According to their website, the Baseline unit is equipped with an AI processor that analyzes live footage to calculate the physical properties of each shot, including speed, trajectory, and player positioning.
4. FoxTenn
FoxTenn is a Spain-based smart tennis court system. It stands out from other existing line-calling systems in that it doesn’t estimate the tennis ball’s trajectory but instead captures the exact moment when the ball hits the court. This is made possible by the combination of multiple high-speed cameras and an on-court laser scanning system.
FoxTenn system’s other task is to collect and generate data for media, players, and coaches. It can, for example calculate the following:
- Player speed
- Ball speed
- Ball angles
- Ball height
- Ball bounce positions
- Player hitting positions
How FoxTenn Works
FoxTenn’s technology’s most distinctive feature is the cameras. FoxTenn uses more than 40 high-speed cameras, which are capable of generating more than 100,000 images per second (2,500 frames per second). Compared to regular line-calling cameras (150 frames per second) these high-speed cameras are almost 100 times more efficient.
In addition to higher frame rates, the high-speed cameras are also synchronized by on-court laser scanners. These laser scanners are also used to track the player’s and the ball’s movement up to the nearest millimeter.
FoxTenn Summarised
FoxTenn line-calling system is an extremely accurate and detailed line-calling system. With the help of high-speed cameras and on-court laser scanners, it can provide exact calls even in difficult conditions. FoxTenn is intended for top-tier professional tennis and it doesn’t provide many features for regular tennis players.
5. Wingfield
Wingfield is an ITF-approved, German-based smart net post system that uses AI to track all aspects of the game. Wingfield consists of a Wingfield Box and a Baseline Camera. The Wingfield measuring unit is very similar to a Zenniz measuring unit.
Wingfield smart net post systems offer features such as:
AI-based system
The Wingfield Box can transform any traditional tennis court into a smart tennis court. The Wingfield box can record video footage from the player’s matches and training sessions. From the recorded footage the AI can analyze the player’s game and provide areas of improvement.
Simple to set up
The system replaces one net post and can be moved from indoor to outdoor courts, depending on the season.
To function, the Wingfield Box only needs power output and an internet connection (ethernet or wireless)
Modular Product Design
The Wingfield Box can be expanded with an additional baseline camera. With the baseline camera expansion, the player’s matches can be recorded from a TV camera perspective.
How Wingfield Works
Wingfield Box is a smart net post fitted with two high-speed cameras, one facing each courtside. The high-speed cameras operate using artificial intelligence to track ball speeds.
The Wingfield Box uses an AI called “Walter,” which can be referred to as Wingfield’s brain. “Walter” has been taught the concept of a tennis ball and a tennis player so it can recognize these objects from the video footage. By understanding these object,s “Walter” can for example,e separate the player from the standing coach and the tennis ball from another flying object.
“Walter has a self-teaching AI model that develops itself with each shot. It can correct itself and learn from the players’ mistakes.
In addition to advanced AI and line-calling the Wingfield Box has two high-speed cameras that can be used to record the player’s matches and practice sessions. Together with advanced AI, the player can use smart filters to find certain key aspects from match recordings, such as errors and serve patterns.
The matches can be recorded from either the net post perspective or the TV perspective with the baseline camera expansion.
In addition to the smart net post and the baseline camera, Wingfield also has an application of its own. With the Wingfield application, a player can access his/her match recordings and statistics and also challenge other Wingfield users to official matches.
The German Tennis Federation has also approved Wingfield, and players can use the Wingfield Box to have their matches officially evaluated for their national ranking.
Wingfield Summarised
Wingfield is a smart net post system that uses a smart net post with integrated cameras to track down ball movements. Wingfield system also offers match and practice session recording options. In addition to line calling and match recordings, Wingfield also offers interactive drills for regular tennis players to learn and improve.
6. In/Out
In/Out is a portable line-calling system that offers accuracy to the millimeter. It contains:
- Portable net device
- Portable line device
- Training exercises
- Stats that can be reviewed and exported
- Free cloud AI coaching
- iOS/Android mobile application
- Streaming option
- CSV/JSON export option
- 1-2 hours battery life
- plug & play
How In/Out Works
In/Out system works by using a portable net sensor and a portable line sensor. The net sensor is attached to a netpost, and it has a built-in touch screen from which the user can see video replays and control the sensor. The line sensor is placed at the back of the court in line with the baseline. With the help of this two sensors, In/Out can perceive the borders of the court and make accurate calls.
In/Out Summary
In/Out is an affordable, convenient, portable line-calling system for all types of tennis players. In addition to line calling it can also generate data from players’ shots, and it can be used for cloud and AI coaching. It is easy to set up and operate.
