For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve ...For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve this problem,a calibration method based on flexible planar target is proposed.In this method,distortion factor is firstly acquired by the invariance of cross ratio,and existing feature points are adjusted with the distortion factor.Then,a large number of points that will be used for the calibration are constructed with the adjusted feature points.Simultaneously,Tsai method is modified so as to reduce the complexity of calibration,which makes the process linear.The simulation and real experiments show that the method proposed in this paper is simple,linear,accurate and robust,and the precision of this method is close to that of Tsai method using abundant points.The method can satisfy the requirement of high precision calibration for camera with large field-of-view.展开更多
High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical appr...High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical approach for examining plasma jets generated by intense laser-plasma interactions.Specifically,we reformulate the fundamental MHD equations to elucidate the governing factors of local plasma density evolution.Furthermore,MHD simulations of laser irradiation on planar targets demonstrate that impact pressure plays a dominant role in the propagation of high-Mach-number plasma jets.In addition,a pronounced dependence on the atomic number is identified:higher-Z materials amplify the impact pressure,suggesting that metallicity exerts a significant influence on the morphology and dynamics of astrophysical jets.展开更多
基金Sponsored by the Fundamental Research Funds for the Central Universities(Grant No.HIT.NSRIF.2014019)
文摘For high precision calibration of camera with large field-of-view,massive calibration points will be needed if traditional methods are selected,which makes the calibration complex and time-consuming.In order to solve this problem,a calibration method based on flexible planar target is proposed.In this method,distortion factor is firstly acquired by the invariance of cross ratio,and existing feature points are adjusted with the distortion factor.Then,a large number of points that will be used for the calibration are constructed with the adjusted feature points.Simultaneously,Tsai method is modified so as to reduce the complexity of calibration,which makes the process linear.The simulation and real experiments show that the method proposed in this paper is simple,linear,accurate and robust,and the precision of this method is close to that of Tsai method using abundant points.The method can satisfy the requirement of high precision calibration for camera with large field-of-view.
基金supported by the National Natural Science Foundation of China(Grant Nos.12325305,12175018,and 12135001)the National Key RD Program of China(Grant Nos.2022YFA1603200 and 2022YFA1603203).
文摘High-Mach-number plasma jets have been extensively investigated in both astrophysical and laboratory contexts.In this work,we revisit the framework of magnetohydrodynamic(MHD)theory and introduce a new analytical approach for examining plasma jets generated by intense laser-plasma interactions.Specifically,we reformulate the fundamental MHD equations to elucidate the governing factors of local plasma density evolution.Furthermore,MHD simulations of laser irradiation on planar targets demonstrate that impact pressure plays a dominant role in the propagation of high-Mach-number plasma jets.In addition,a pronounced dependence on the atomic number is identified:higher-Z materials amplify the impact pressure,suggesting that metallicity exerts a significant influence on the morphology and dynamics of astrophysical jets.
