Connect and configure cameras
For the physical setup (lighting, placement, background), see optimize your capture space and record with multiple cameras. This page is about the cameras themselves and the settings that affect calibration stability.
Supported cameras
Any USB camera OpenCV's VideoCapture can open should work. Tested
configurations:
| Camera | Resolution | FPS | Notes |
|---|---|---|---|
| Logitech C920 | 1080p / 720p | 30 / 60 | Widely used, reliable |
| Logitech C922 | 1080p / 720p | 30 / 60 | Similar to C920, better low light |
| Logitech Brio | 4K / 1080p | 30 / 60 | Higher resolution, wider field of view |
| Elgato Cam Link | 1080p | 60 | HDMI capture, for use with a DSLR or mirrorless camera |
| Generic USB webcams | Variable | Variable | May work, quality varies |
USB bandwidth
USB cameras use real bandwidth, and running out of it shows up as dropped frames or disconnects, not a clear error message. A few things that help:
- Use separate USB controllers when you can, not just separate ports on the same hub.
- USB 3.0 has more headroom than USB 2.0.
- Lower resolution means less bandwidth per camera, which means more cameras can share one controller.
- If cameras are dropping frames or disconnecting, that's the first thing to check, spread them across controllers before assuming something else is wrong.
Configuration settings that matter
Set through the Camera Config Tree in the sidebar:
| Setting | Recommendation |
|---|---|
| Resolution | 720p is a good balance of quality and bandwidth |
| Framerate | 30 FPS minimum, 60 FPS for fast movement |
| Exposure | Manual, fixed |
| Focus | Manual, fixed on the capture volume |
| White balance | Manual, fixed |
Fixed exposure and focus matter more than they might seem to. If auto-exposure changes mid-recording, the detected feature positions shift with the brightness change, and your calibration can drift as a result. This is a common, non-obvious cause of a calibration that looked fine and then didn't.
Synchronization
Cameras aren't hardware-genlocked, FreeMoCap synchronizes them in software by aligning frame timestamps after the fact. For the most reliable sync: use cameras that hold a consistent framerate (not variable frame rate), and keep individual recording sessions under about 30 minutes to limit how much drift can accumulate.
Calibration board
Calibration uses a printed ChArUco board. Print it on something rigid so it stays flat, board files are in the software's repository. The board's physical dimensions need to match whatever's configured in the calibration settings.