Research On Self-calibration Method For Stereoscopic Vision Space Coordinate Measuring System With Large Field

This paper is based on the Stereoscopic Vision Space Coordinate Measuring System located in mountainous area and designed by the laboratory.There are more than 20 cameras in the whole system,and the monitoring area of this system is up to 5 square kilometers.Under the conditions of large monitoring area and different focal lengths and spatial positions of each camera,this paper studies calibration methods for large field of view.The main research contents and innovations of this paper are as followed:1.The first part of the paper introduces the research background and the significance of this subject.The research status of camera calibration method is classified and explained,and the advantages and disadvantages of existing camera calibration methods in large field of view are analyzed.2.The Stereoscopic Vision Space Coordinate Measuring System is presented in the second part.This paper explains the constitution and principle of the system in detail.3.In the third part,a simplified camera imaging model is proposed.The paper elaborates the camera imaging model under ideal conditions,and cuts the number of camera calibration parameters to 4 based on this model.4.A new calibration method for single camera is proposed.Firstly,this method obtains BDS coordinates of two calibration points and the camera with the BeiDou Navigation Satellite System,then the pixel coordinate of calibration points are read,finally the calibration of the focal distance and the rotation angle are realized step by step according to the equality of opposite angles and the nonlinear least square method.According to the simulation analysis,the relative error of camera calibration results is less than 0.30%,and the relative error of space coordinate measurement is less than 0.5%within the circular monitoring range of 200m in diameter.Meanwhile,the experimental results show good agreement with the simulation.Via this method.the calibration process is simpler and faster,and the accuracy meets the requirement of this system.5.A new self-calibration method for stereoscopic vision system is proposed,which is based on the epipolar geometry model.This method extracts matching feature points of the images captured by two cameras in the system,then calculates the fundamental matrix and the essential matrix according to the matching results.After that,the internal and external parameters are resolved using the matrices,thus the calibration work of two cameras in stereoscopic vision system can be completed synchronously.The experimental results show that the space coordinate measurement error via this method is less than lm,and the relative positioning error is less than 0.50%.This method eliminates the layout process of the calibration points,further simplifies the calibration process and improves the calibration speed.6.Finally the paper summarizes the two calibration methods,and points out the direction of future improvement.