Multi-channel signal parameters joint optimization for GNSS terminals

In order to achieve a high precision in three-dimensional (3D) multi-camera measurement system, an efficient multi-camera calibration method is proposed. A stitching method of large scale calibration targets is deduced, and a fundamental of multi-camera calibration based on the large scale calibration target is provided. To avoid the shortcomings of the method, the vector differences of reprojection error with the presence of the constraint condition of the constant rigid body transformation is modelled, and minimized by the Levenberg-Marquardt (LM) method. Results of the simulation and observation data calibration experiment show that the accuracy of the system calibrated by the proposed method reaches 2 mm when measuring distance section of 20 000 mm and scale section of 7 000 mm × 7 000 mm. Consequently, the proposed method of multi-camera calibration performs better than the fundamental in stability. This technique offers a more uniform error distribution for measuring large scale space.