Rocket Height

Room

Use the same room on the laptop and both phones.

A · connecting

Camera A

Allow camera and motion access. Keep this page open.

CAMERA A · iPhone 8not connected

Waiting for camera A

CAMERA B · iPhone 11not connected

Waiting for camera B

Connection

Room:

Open this HTTPS page on the laptop and both phones.

Setup

A to launcher (m) A lens height (m) A fallback vertical FOV B to launcher (m) B lens height (m) B fallback vertical FOV A to B distance (m) Calibration pole height (m) Tape uncertainty ± (m) Click uncertainty ± (px) Phone angle uncertainty ± (°) Expected top height (m) Expected drift radius (m) Frame margin (degrees) Launch pad off-screen after calibration

Calibration only: the pole base must be at the launch point and visible in both cameras while you mark BASE and TOP. Press each mark three times, then LOCK SETUP and CALCULATE SETUP. After calibration, remove the pole. When “Launch pad off-screen after calibration” is selected, you may tilt each phone straight backward/upward so the launch pad leaves the recording frame. Do not pan left/right, twist the phone, change lens, zoom, resolution or orientation. The phone angle captured at recording start is applied to the 3D sight rays.

Enter the expected height and camera distances.

Not calibrated

Record

Length (seconds)

The live preview remains connected before, during and after recording. Recording is stored locally on each phone, then transferred without stopping the camera.

Review

Live preview

0.00010.0

A sync offset (frames) B sync offset (frames)

Arrow keys move the shared timeline. Fine-tune B until the first rocket movement or launch sound occurs on the same frame in both videos.

Measure

At the same chosen frame, mark the centre of the rocket in both videos. The launch pad is not required in the recorded frame. In off-screen mode, the saved calibration pose and recording-start phone angle locate the sight rays. Only tilt straight upward after calibration; sideways panning, twisting, changing zoom/lens or changing the video crop invalidates the saved direction. Use W/A/S/D to nudge the last mark by one source pixel; hold Shift for five pixels.

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