gps-denied-onboard/_docs/00_problem/problem.md

We have a wing-type UAV with a fixed downward navigation camera that can take photos 3 times per second. The authoritative navigation-camera spec is defined in `restrictions.md` as the ADTi 20MP 20L V1, APS-C sensor, about 5472 x 3648 px; older higher-resolution references are superseded. Also plane has flight controller with IMU. During the plane flight, we know GPS coordinates initially. During the flight, GPS could be disabled or spoofed. We need to determine the GPS of the centers of the next frame from the camera. And also the coordinates of the center of any object in these photos. We can use an external satellite provider for ground checks on the existing photos. So, before the flight, UAV's operator should upload the satellite photos to the plane's companion PC. 
The real world examples are in input_data folder, but the original still-image set has a much larger distance between photos than the target aircraft will have. On that particular example photos were taken 1 photo per 2-3 seconds. But in real-world scenario frames would appear within the interval no more than 500ms. Additional representative data is available in `input_data/flight_derkachi/`: cropped nadir flight footage plus synchronized `SCALED_IMU2` and `GLOBAL_POSITION_INT` telemetry. This supports video/telemetry synchronization, replay, latency, VIO smoke tests, and trajectory comparison against the tlog GPS path. Camera intrinsics, lens distortion, raw camera feed parameters, and exact camera-to-body calibration are still pending, so final production accuracy claims remain gated on calibration data or a separately surveyed representative dataset.