How to film a sprint so it can be measured

The setup, step by step

1. 01Pick the section to measure

   Every measurement is computed inside a rectangle on the ground whose width and length you give. On an athletics track, the lane lines give the width for free: a regulation lane is 1.22 m wide.

   For the length, use the painted marks. In the 100 m hurdles the hurdles are 8.50 m apart (first one 13 m from the start), in the 110 m hurdles 9.14 m (first one at 13.72 m). One hurdle interval in your lane makes a perfect rectangle, long enough to see at least two ground contacts at full speed. Anywhere else, a tape measure and four cones will do.

2. 02Set the phone down, then leave it alone

   A tripod or a steady stand, phone in landscape, side-on and square to the track, roughly facing the middle of the section, ideally at head height. Step back until the whole section is in view with room to spare on each side: the athlete must stay fully in frame while crossing it.

   Once recording starts, nothing moves. The calibration assumes a still camera: a handheld video, or one that follows the athlete, cannot be measured.

3. 03Set up the camera

   • Main lens (1x). No ultra-wide (0.5x), which bends the edges of the picture, and no zoom.
   • 60 frames per second in normal video mode, not slow motion. Above that, TrackGenius brings the video down to 60 frames per second.
   • The highest resolution offered, 1080p at least.
   • Full light, daylight if possible: a dark picture means motion blur, and blur degrades body detection.

4. 04Run

   One athlete analysed per video, in the lane you will declare. Other people can appear in the picture, you pick the right one later, but keep them from hiding the athlete. Fitted clothing helps locate the joints.

   Start recording before the start and stop after the athlete leaves the section. The video can last up to a minute, and you then choose a window of five seconds at most, the one where the athlete crosses the section.

5. 05Place the four points in TrackGenius

   After the upload you trim the sequence, click the four corners of the section on a frame of the video, and give the surface, the width, the length and the athlete's lane. Place each point as precisely as you can, on the exact crossing of the lines: every distance follows from those four clicks. You then pick the athlete, and the result arrives within a few minutes.

The mistakes that make a video unusable

• Following the athlete with the phone. Mistake number one: a pan, even a slow one, breaks the calibration.
• Zooming while filming, or filming with the ultra-wide lens.
• A corner of the section hidden, by a bag, a hurdle, another athlete, or cut off by the edge of the picture.
• Filming from the front, from behind or at a sharp angle: side-on is the view the calibration expects.
• Standing too close: the athlete leaves the frame while crossing the section.
• Filming at dusk without floodlights: motion blur makes the ground contacts undetectable.

Why the setup matters this much

A video holds no metres. The four markers, whose real size you give, are what tie pixels to the ground: without them there is no telling whether the athlete ran 8 m or 12 m. The declared lane and the athlete's height, set in their profile, then fix the depth, which a single camera cannot see. That is what turns a plain phone video into a 3D skeleton and measurements in metres, seconds and degrees.

Frequently asked questions

In short

• Phone fixed on a tripod, side-on, square to the track, at head height, no zoom and no panning.
• A rectangle on the ground of known size, its four corners visible: one 1.22 m lane between two hurdle marks (8.50 m in the 100 m hurdles, 9.14 m in the 110 m hurdles).
• 1x lens, 60 frames per second in normal mode, full light, one athlete analysed, a window of five seconds at most.