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Oleksandr Bezdieniezhnykh
94d2358c8b
Derkachi e2e Tier-2 divergence had three stacked root causes; this
commit ships fixes for all three plus the IMU prerequisite they
depend on, plus a baseline cheirality gate for cv2.recoverPose.
AZ-918 MAVLink IMU adapters now convert raw mG/mrad-s + FRD body to
SI m/s^2 + rad/s + FLU body via helpers.imu_units. Without
this the ESKF receives values ~1000x too small with wrong-
sign Y/Z and cannot function at all.
AZ-919 Composition root wires EskfNominalAltitudeProvider into the
KLT/RANSAC strategy via the AZ-331 factory introspect path;
OKVIS2 and VINS-Mono are unaffected.
AZ-920 KLT/RANSAC recovers metric translation via Ground Sampling
Distance when AGL is available; otherwise falls through with
scale_quality=direction_only/unknown (no fake scale invented).
AZ-921 VioOutput.scale_quality signal; ESKF add_vio adapts R_meas
position block based on the flag (1e6 inflation when scale is
direction_only/unknown to keep the filter consistent).
AZ-922 KLT/RANSAC cheirality gate rejects single-frame rotations
beyond a config threshold (default 30 deg), catching
cv2.recoverPose twisted-pair flips that cause immediate ESKF
divergence on low-parallax aerial scenes.
Verification:
- Tier-1 (macOS) unit suite: 2346 passed, 0 failed.
- Tier-2 (Jetson) Derkachi e2e: divergence moves from frame 5
(mahalanobis^2 3757) to frame 233 (mahalanobis^2 212). Remaining
drift is open-loop attitude accumulation, not cheirality.
Follow-up tickets filed:
- AZ-923 closed as misdiagnosed: EskfNominalAltitudeProvider was
already correct (nominal_pos.z IS the AGL when takeoff origin sits
at ground level); the early-frame AGL near zero reflects the drone
being stationary on the ground, not a provider bug.
- AZ-942 filed: cross-check VIO rotation against IMU preintegrator
(consistency gate) - more physically grounded than the coarse
AZ-922 threshold and likely required to absorb the frame-233 drift.
Co-authored-by: Cursor <cursoragent@cursor.com>