In view of the limitations of the existing methods when the camera has no common field of view, this paper proposes a method of using two plane calibration plates to calibrate two cameras at the same time. By deriving the coordinate transformation between the two cameras and two calibration plates, the solution of the relative pose relationship between any camera and the reference camera is transformed into a more mature hand-eye calibration equation. The experimental results show that this method can achieve simultaneous calibration of two cameras, and the absolute error is less than 0.089 mm. In the dual vision 3D measurement system, the cumulative error with phase height is less than 0.116 mm, which can provide a reliable initial value for the next step of data fusion.
Method of simultaneous calibration of dual view 3D measurement system
First published at:Mar 22, 2021
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The fringe projection measurement method is widely used in various fields due to its simple structure, high precision, and resolution, full field measurement, etc. The research on the single-view system of the fringe projection measurement method has been relatively mature. The dual-view fringe projection measurement system is an extension of the single-view fringe projection measurement system, a larger range of three-dimensional geometric information can be obtained by expanding the camera's field of view. In the dual-view fringe projection measurement system, the three-dimensional measurement results of the subsystem are always restored in the camera coordinate system, while the two camera coordinate systems are independent of each other in the dual-view fringe projection measurement system. Therefore, it is necessary to solve the transformation relationship between the two camera coordinate systems, the pro-cess of solving the transformation relationship between the two camera coordinate systems is called global calibration. Global calibration is the most important task in the calibration of dual and multi view systems. However, the existing global calibration methods require expensive auxiliary equipment when the two cameras have no common field of view, which adds a certain cost to the calibration, and when the viewing angle of the system is more than two, the method of relying on the auxiliary equipment is limited. Aiming at the limitations of the existing global calibration methods, this paper proposes a method to achieve dual-view global calibration by using two plane calibration boards: Firstly, through a series of derivation, the problem of solving the transformation matrix between the two camera coordinate systems is transformed into the problem of solving the hand-eye calibration equation which is more mature in the field of robot; Secondly, adjust the two calibration boards to the appropriate position according to the placement of the camera, and fix the two calibration boards; Thirdly, place the two calibration boards at several positions in the field of view of the two cameras at the same time to obtain several equations; Finally, the conversion matrix between the two cameras is obtained by using the quaternion method, least square method, and nonlinear optimization. The method identified in this paper does not require additional auxiliary equipment, and it is proved by quantitative experiments: this method can realize the calibration of dual cameras simultaneously and the absolute error of the method does not exceed 0.089 mm, which is relatively reliable; in the dual-view 3D measurement system, the cumulative error of global calibration and phase-depth does not exceed 0.116 mm, which can provide a reliable initial value for further data fusion. In addition, the global calibration method determined in this paper is suitable for multi-view 3D measurement systems. When the number of cameras is more than two, the calibration board corresponding to the number of cameras can be added to achieve simultaneous calibration of multiple cameras.
Get Citation: Zhao Hanzhuo, Gao Nan, Meng Zhaozong, et al. Method of simultaneous calibration of dual view 3D measurement system[J]. Opto-Electronic Engineering, 2021, 48(3): 200127.
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