Court Vision
Auto-charting tennis matches from broadcast video
1. Teaching a Computer to Watch Tennis
Can a computer watch a tennis broadcast and write down every shot, the way a courtside volunteer does by hand?
5 min read2. M0: Can SAM 3 Hold Onto a Tennis Ball?
An AI that finds objects by description can't tell one tennis ball from six on court — until you point at the one in play.
7 min read3. M1: From Pixels to Meters
How four painted corners taught the software to turn a TV picture of the court into a real, to-scale court diagram — for free.
7 min read4. M2: The Court Doesn't Return Serve
Teaching software to spot every hit and bounce in a rally, just from watching the ball's path bend.
7 min read5. M3: Who Hit That?
The software found the players by noticing who never moved, then called every forehand and backhand from where the ball crossed their body.
8 min read6. M3: The Cutting Room
Most of a tennis broadcast isn't the match — the software has to spot the one camera angle that actually shows it.
7 min read7. M3: The Static Camera Isn't
The 'still' broadcast camera actually drifts mid-point — and that breaks a free trick for spotting players in video.
6 min read8. M3: The Toss Is the Bootstrap
The serve toss lets the software find the ball itself, and it charts its first full point without a human drawing a single box.
4 min read9. M3: The Ball Gets a Vote
When the software can't tell who hit the ball, it holds a vote instead of guessing — and the ball outvotes the serve call, on camera.
8 min read10. T1: A Test Set With Answers in the Back
The software faces its first honest test against a match a human already scored, and the camera math needs fixing first.
6 min read11. T1: Right Hardware, Wrong Sign
Graded against a real human chart for the first time, the system's biggest miss was a lefty problem, not a broken tool.
5 min read12. The $0 Specialist and the Load-Bearing Bug
A free specialist replaces an expensive all-purpose tracker — and exposes that its rival's biggest flaw was secretly marking the end of every point.
6 min read13. The Score Bug Is the Point ID
A TV scoreboard graphic nobody notices turns out to be the only reliable way to tell where one point ends and the next begins.
7 min read14. Within One Token of a Human
The project finally gets an honest report card: how many fixes would turn the machine's chart into a human's? Today's first answer: 2.2%.
11 min read15. The Draft Grades Itself
A confidence flag tells a volunteer chart-corrector which draft points to trust — and this post checks whether the flag itself can be trusted.
8 min read16. The Benchmark Grows Up
A bigger test made the trust score honestly drop — then a check that could never fail got caught, and the score climbed back up.
10 min read17. The 33rd Charter
Court Vision introduces itself to the real volunteers who chart tennis matches by hand, and asks whether its drafts actually save them time.
7 min read18. Nobody Sees the Ball Land
The machine couldn't tell wide errors from deep ones. The fix: stop trying to watch the bounce and calculate it, like Hawk-Eye does.
7 min read19. The Machine Grows Ears
The ball tracker blinks at the worst moments. Broadcast microphones don't. The software learns to listen for the pock of strings on ball.
6 min read20. The Court That Fits Itself
A human has clicked four corners for every match this project ever charted. A free pretrained network just took the job — and knew when to refuse it.
5 min read21. Stick Figures Beat Smudges
The forehand-or-backhand call has been stuck for two weeks. The fix: draw a skeleton on every player and read the actual swing.
5 min read