Air time jump (air_time_jump)

Measure vertical jump height from air time only (no user height required).

Measure vertical jump height from air time only.

This mode does not require userHeightCm.

See also:

• Shared query parameters (Tracking + Upload Tracking)

• Upload Tracking endpoint (video & image)

• WebView messages (Upload Tracking)

Overview

What you get

• Live jump detection and jump height estimates.

• No explicit calibration step.

• Height computed from a simple physics model.

Key features

• Uses only hip keypoints (left_hip, right_hip).

• Dynamic baseline keeps tracking robust without calibration.

• Works in real time (/pose_tracker/tracking) and on video (/pose_tracker/upload_tracking).

Prerequisites

Required query parameters

• exercise=air_time_jump

• token=...

Optional query parameters

• devicePitchDeg=... (number, degrees)

  • Accepted for consistency.

  • Height is driven by air time.

Tracking prerequisites (pose)

• Both hip keypoints must be detected with score > 0.5.

• The full body should be visible.

• The camera must stay fixed.

Comparison: jump_analysis vs air_time_jump

Use this when user height is unknown.

Aspect	jump_analysis	air_time_jump
User height	Required (userHeightCm)	Not required
Calibration	Yes (stable standing → baselineY + cmPerPixel from frame height)	No (dynamic baseline from recent frames)
Scale	Pixel-to-cm via cmPerPixel	Time-to-height via physics
Formula	jumpHeightCm = (baselineY - minY) * cmPerPixel	h = (1/8)*g*t², then cm
Outputs	jumpHeightCm, deltaPixels, cmPerPixel, baselineY, minY	jumpHeightCm, airTimeMs, airTimeSeconds, baselineY, minY
Use when	User height is known; you want a scale tied to frame/user	User height unknown; you want a simple, physics-based estimate

Also see: Jump analysis (jump_analysis)

Exercise detection

Always pass exercise=air_time_jump to enable air-time jump mode.

API endpoints

Live (camera)

Base URL:

https://app.posetracker.com/pose_tracker/tracking

Example:

https://app.posetracker.com/pose_tracker/tracking?token=YOUR_API_KEY&exercise=air_time_jump

Upload Tracking (video)

Base URL:

https://app.posetracker.com/pose_tracker/upload_tracking

Example:

https://app.posetracker.com/pose_tracker/upload_tracking?token=YOUR_API_KEY&source=video&exercise=air_time_jump

Common optional flags on video:

• export=true (keeps the last frame visible and enables export UI)

• skeleton=true|false

• keypoints=true (plan-gated)

PostMessage events

These events are sent from the iframe/WebView to your host app.

If you’re new to placement messages, read: Exercise Placement.

posture

{
  "type": "posture",
  "message": "...",
  "direction": "in-frame",
  "ready": false,
  "requirements": []
}

jump_started

Sent once when upward movement crosses the trigger threshold.

{
  "type": "jump_started"
}

jump_height

Sent during measurement and at the end of a jump.

{
  "type": "jump_height",
  "jumpHeightCm": 29.7,
  "airTimeMs": 492,
  "airTimeSeconds": 0.492,
  "baselineY": 510.1,
  "minY": 355.8,
  "measuring": true,
  "landed": true,
  "final": true
}

Notes:

• airTimeMs covers the full airborne duration (takeoff → landing).

• Unlike jump_analysis, there is no cmPerPixel field.

jump_summary (video)

Sent at the end of a video analysis.

Multiple jumps can be detected in a single clip.

Heights are in centimeters.

Air times are in seconds.

{
  "type": "jump_summary",
  "totalJumps": 4,
  "avgJumpHeight": 28.8,
  "maxJumpHeight": 33.5,
  "minJumpHeight": 22.1,
  "avgAirTimeSeconds": 0.48,
  "maxAirTimeSeconds": 0.53,
  "minAirTimeSeconds": 0.41,
  "final": true
}

error

{
  "type": "error",
  "message": "..."
}

Placement overlay behavior

• Uses the standard placement system (posture).

• Baseline is computed dynamically from recent hip Y values.

• Baseline can be locked when jump starts, and released after landing.

User flow

1. Placement: wait for posture.ready=true.

2. Jump:

   • Receive jump_started.

   • Receive jump_height updates.

   • Consider the jump complete when jump_height.final=true.

Measurement algorithm

1) Hip signal + baseline

• Read left_hip and right_hip keypoints.

• Require score > 0.5.

• Keep a rolling window of recent hip Y values.

• Use that window to estimate a dynamic baselineY.

2) Jump detection + landing

• Jump starts when upward movement exceeds 20 px from baseline.

• A few consecutive frames are required to avoid false triggers.

• Landing occurs when hip Y returns within 20 px of baseline.

3) Air time

• Measure air time t from jump start to landing.

t = (landingTime - startTime) in seconds

4) Height from physics

Use the vertical motion relationship:

• time up = time down = t/2

• initial vertical velocity at takeoff: v = g * (t/2)

• max height: h = v² / (2g) = g * t² / 8

Formula (meters):

h = (1/8) * g * t^2

Where:

• g = 9.81 m/s²

• t in seconds

Convert to centimeters:

jumpHeightCm = h * 100

Integration examples

Web (iframe)

<iframe
  id="posetracker"
  src="https://app.posetracker.com/pose_tracker/tracking?token=YOUR_API_KEY&exercise=air_time_jump"
  style="width:100%;height:100%;border:0;"
  allow="camera;microphone"
></iframe>

<script>
  window.addEventListener('message', (event) => {
    const msg = event.data;
    if (!msg || !msg.type) return;

    switch (msg.type) {
      case 'posture':
        break;
      case 'jump_started':
        break;
      case 'jump_height':
        // msg.jumpHeightCm + msg.airTimeSeconds
        break;
      case 'jump_summary':
        break;
      case 'error':
        console.error(msg);
        break;
    }
  });
</script>

Upload Tracking (video URL)

https://app.posetracker.com/pose_tracker/upload_tracking?token=YOUR_API_KEY&source=video&videoSrc=https://your-cdn.com/jump.mp4&exercise=air_time_jump&export=true

When export=true, the last analyzed frame stays visible.

Best practices and limitations

Best practices

• Use a high FPS camera when possible.

• Keep the camera fixed and avoid motion blur.

• Ensure clear landing visibility (hips must be tracked).

Limitations

• This assumes a mostly vertical ballistic jump.

• Arm swing and knee tuck can change air time.

• Landing detection is hip-based, not foot-contact-based.