<aside> 💡 This section guides you through best practices for camera setup, calibration, and data collection using our motion capture system.

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High level best practices

• Ensure you are connected to a stable Internet connection. Video upload may fail with a poor connection.
• Do not move cameras once you've passed the calibration step. If you accidentally moved a camera, start a new session.
• The checkerboard is only used for calibrating the cameras, you can remove it after successfully completing the calibration step.

Watch our tutorial webinar and browse our Q&A to learn more about best practices

https://www.youtube.com/watch?v=7Xk8-K7A3Zk

🤳 Camera setup

• Use tripods to hold the smartphone in fixed position during the session(s)
• The rear-facing camera is the one used for recording, position the smartphones accordingly
• Position the cameras to avoid segment occlusions during the task
  • At least two cameras need to see every body segment at all times during the movement. Two cameras is sufficient for many tasks, but tasks where segments get occluded may benefit from an additional (front-facing) camera (e.g., single-leg activities).
  • For a two-camera setup, cameras at 30-45° off of the line facing forward from the participant is typically best. Pure sagittal views do not work well due to limb occlusion.
• Avoid people in the background. Our algorithms are built to handle this, but it will make them slower and error prone.
• We recommend doing a short test with the participant performing the task of interest and checking that the participant remains visible in each camera during the entire activity before calibrating the cameras. That ensures that they remain within the field of view for the whole duration of the session.
  • Feel free to position the smartphone in either landscape/horizontal or portrait/vertical positions. If you position the camera in landscape mode, make sure portrait orientation is not locked in your device settings. If it is, the iOS app should display a warning. Otherwise, videos will be recorded in landscape format but with a portrait orientation, leading to poor motion reconstruction.
• Avoid having the participant exit and re-enter the capture volume.

The following video describes how to set up your capture volume for overground gait. The approach is valid for most use cases (i.e., other movements).

https://www.youtube.com/watch?v=LPHeq7bxP38&ab_channel=OpenCap