## Ground Plane Orientation Analysis
- `calibrate_extrinsics.py` uses `--auto-align` to rotate the world frame.
- Alignment maps a detected face normal to `[0, 1, 0]` (Y-up).
- Heuristic detection (`detect_ground_face`) depends on camera being roughly upright.
- `inside_network.json` uses a world frame where the ground is at Y=0 and cameras have specific offsets (e.g., -1.17m Y).