Tennis Serve
Serve review in two blocks, setup and load, then execution and finish: stance, shoulder tilt, knee bend, toss, racket drop, contact height and landing.
How far has this tool been checked?
The measurements were checked against computer-drawn athletes whose true answers are known exactly. That shows the arithmetic and the event rules are right under clean, controlled conditions. It does not measure how well the body-tracking model sees real people (water, loose clothing, crouching, fast limbs) and has not been compared with a lab or a coach’s stopwatch. Treat the numbers as an aid, and use the confidence label beside each value.
Where the camera goes
Seen from above. Angles are measured round from the front of the athlete; 90° is square-on from the side. Reference line: direction of the serve.
Side or slight rear-side angle. Tossing arm, knee bend, racket drop, contact height and landing distance.
How high, and how it should sit
Framing
The whole action: athlete, toss and landing.
The 50–75% band is our own guidance. No published source gives a camera distance in metres, so use it as a starting point and adjust until the whole movement fits.
Ready to record?
Tick each item as you set it up. This is a reminder, not a lock.
0 of 10 ready
All the camera settings
Every setting shows where it came from.
- Camera height
- No height is given.
- Our guidance
- Distance
- No published distance exists. Stand back far enough that the full movement (arm circle, stride, follow-through) stays in frame with room to spare. Use the 1x lens and move your feet, not the zoom. Leave room above the athlete for the peak of the toss and in front for the landing.
- Our guidance
- Frame rate
- 60+ fps. 60 fps preferred. Slow motion saved at normal speed works if you enter the recorded frame rate.
- From published guidance
- Resolution
- 1080p minimum, or better
- From published guidance
- Orientation
- Landscape or portrait both work.
- From published guidance
- Lens and zoom
- Avoid zoom settings or fisheye lenses that distort the body lines.
- From published guidance
- Lighting
- Bright, even light.
- From published guidance
- Stability
- Tripod or fixed support, level with the horizon.
- From published guidance
- Calibration
- No calibration is needed for angles. Distances and speeds need a scale (see Calibration).
- From published guidance
Before you start
- Keep the server the clearest subject in view, with the toss and racket visible.
- Fix setup and load inconsistencies before judging toss or contact numbers.
- Pick one or two priorities per session.
Cues for the athlete
Plain coaching cues, one thing at a time.
No cues are published for this tool.
Why camera position matters
Research behind these rules.
2D angles are only trustworthy when the limb moves in the plane the camera sees. Camera-side joints are measured more accurately than far-side joints, and timing is only as fine as one frame.