Calibrate your cameras
To get 3D data from several cameras, FreeMoCap first needs to work out where each camera is. You do this by recording a printed ChArUco board as you move it around in front of the cameras.
A single camera doesn't need calibration.
1. Print a ChArUco board
FreeMoCap works with two boards. Use the 5x3 board unless you have a reason not to. Its squares print larger, so cameras can see it from farther away.
| 5x3 board (5 squares wide, 3 tall) | 7x5 board (7 squares wide, 5 tall) |
|---|---|
 |  |
Print it and glue or tape it to something stiff, like cardboard. The board must stay flat. For a large space, print it bigger, for example as a poster.
Then measure one black square in millimeters. FreeMoCap needs the exact size to get your measurements right.
2. Set up your cameras
Connect two or more cameras (three is better), each plugged straight into the computer. Place them so they all see the area where you'll move, from different angles. See record with multiple cameras and optimize your capture space.
Click Connect Cameras.
3. Enter your board's details
In the Calibration panel, open the board settings and set:
- The board preset: 5 x 3 or 7 x 5, to match your printout.
- The square length: the size you measured, in millimeters.
To have FreeMoCap use the board to set which way is up and where the floor is, turn on
Align to initial Charuco ground plane, and start the recording with the board lying flat on
the floor. See set the ground plane.
4. Record the calibration
- Click Calibrate, then Record and Calibrate.
- Hold up the board and move it slowly through the space. Tilt and turn it as you go. Make sure every camera sees the board at the same time as at least one other camera.
- Click Stop Recording & Calibrate.
FreeMoCap calibrates as soon as you stop. When it finishes, the panel shows Calibrated.
If you already have calibration videos, use Calibrate > Import Calibration videos instead. To reuse a calibration file from before, use Calibrate > Import .toml file.
5. Record your motion capture
Leave the cameras where they are. If you move one, calibrate again.
Click Start Recording, perform your movement, and click Stop Recording. FreeMoCap processes the recording with your calibration.
To process a recording again, open it in the Playback tab, click Continue to Mocap Setup, then Process Mocap.