Large-Field binocular vision attitude determination method for rocket recovery

Abstract. Accurate attitude estimation is essential for stable guidance and control during rocket recovery, yet it remains challenging because the target undergoes rapid pose changes, occupies only a limited image area over a large observation corridor, and often exhibits weak texture and approximate axial symmetry. To address these issues, this paper proposes a large-field binocular-vision-based attitude determination method for rocket recovery. First, a distortion-aware stereo calibration strategy based on stitched control points is developed to enable reliable geometric modeling over a large measurement field with a portable calibration target. Second, a robust contour extraction pipeline is constructed by combining bilateral filtering, gradient enhancement, and multi-threshold Canny fusion. Third, the rocket central axis is reconstructed by fitting 2D midlines in rectified stereo images and intersecting their corresponding back-projection planes, which improves stability over point-wise triangulation. Finally, pitch and yaw are derived from the recovered 3D axis direction, while roll is estimated by phase correlation on the polar-unwrapped base image under a temporal continuity constraint. Experiments on a 1:20 cylindrical scale model show RMS reprojection errors of 0.056 px and 0.066 px for the left and right cameras, respectively, and a 3D checkpoint RMSE of 33.42 mm. On a 100-frame sequence, the proposed method achieves RMSEs of 1.58°, 1.54° and 1.41° for roll, pitch, and yaw, respectively, outperforming ORB+PnP, SGBM, and Chamfer-based baselines. The results demonstrate that the proposed method provides an accurate and practical optical solution for external attitude measurement in rocket-recovery scenarios.