Research On The Parameters Calibration Of Intersection System For Spatial Coordinate Detection

Accurate measurement of the spatial location of the blast point is very important to test the effectiveness of the weapon system.The intersection method based on multi-camera image acquisition and analysis provides an excellent solution for spatial coordinate testing,and the accurate acquisition of system parameters of the test model is the key to obtaining high accuracy test results.In this paper,we adopt the "binocular isometric intersection" approach to test the spatial position of the near-Earth bombing point.Mainly analyzed the spatial position measurement of the unknown point and the parameter calibration technique.In this paper,we firstly derived the formula for solving the target position under the ideal co-linear pair view intersection,based on which,we further analyzed the formula for solving the target position when the main points of the cameras are not co-linear and with declination angle exists in the actual test state.Mathematical simulations were designed to realize the process of inputting known spatial positions to obtain the imaging points of the target point on the two cameras respectively.Through inputting the imaging points to obtain the spatial coordinates of the target point,which verified the correctness of the measurement model.The effect of different system parameter errors on the testing accuracy was further investigated by changing the data input to the system.After the further analysis of the measurement model,the parameters to be calibrated are determined and a system calibration scheme is constructed.According to the calibration principle,an improved joint calibration method of binocular camera with line-intersection is adopted.The system coordinate system is established on the virtual spatial target surface formed by the intersection of the dual cameras,and it is used as the reference surface for the projection of the target point on the system coordinate system.A transparent double-sided high-precision target plate is used,and the internal and external parameters of the camera are fitted by the object coordinates of the common point on the joint target plate.Based on the camera parameters obtained from the calibration,the system parameters to be found,such as the coordinates of the main point of the optical lens and the coordinates of the image point of the target point projected on the virtual target surface are deduced.For the demand of 1000×1000×1000mm3 the test device of "binocular isometric intersection" is designed and built.The calibration of the system parameters is completed,and the derived system parameters are brought into the spatial coordinate solution equation to obtain the spatial coordinates of the unknown point.The test results show that the coordinate errors are less than±20mm,and the calibration algorithm of the intersection measurement system which constructed in this paper is effective and feasible.