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Capture Volume: Extrinsic Calibration

Processing steps

  1. Save videos to project_root/calibration/extrinsic/ according to the naming convention outlined in Project Setup
  2. Ensure that videos were synchronized when recording, or provide a frame_time_history.csv file so that caliscope can perform the synchronization during processing.
  3. You may need to reload the workspace for the Calibrate Capture Volume button to become enabled
  4. Pressing Calibrate Capture Volume will initiate the calibration. The final log statement at complete will indicate that point_esimates.toml has been saved. at this point you can reload the workspace and the Capture Volume tab will become enabled.
  5. On the Capture Volume tab you can visually inspect the relative position of the cameras according to the calibration
  6. Set the board origin to a given frame to align the world frame of reference with the board position. This can be refined by flipping the axes.

Practical Recording Guidelines

  1. Ensure Coverage and Overlap:

    • Cover the entire volume where the cameras' fields of view overlap with the Charuco board movements.
    • Ensure there's sufficient overlap in the fields of view of the different cameras. This overlap is critical for multi-camera calibration.

  2. Use a board with sufficiently large squares

    • Larger ArUco markers can be identified from farther away allowing a larger capture volume to be calibrated.

  3. Minimize motion blur

    • motion blur can substantially compromise corner recognition
    • using a higher frame rate can reduce motion blur
    • this will require more light to maintain good illumination

  4. Consistent Focus:

    • Use manual focus if available to keep the focus consistent throughout the filming.
    • Auto-focus can introduce inconsistencies

  5. Use the board to define the origin

    • this is for convenience and not a strict requirement
    • touch the board to the ground while it is held vertically
    • ensure that the top left corner of the board (as shown on the Charuco tab) is in view of the camera and touching the ground