The Research Of Radiation Simulation And Parallel Computation In Remote Sensing Ground Test Field

Remote sensing ground test field is mainly used for basic research of remote sensing technology,that is,the mechanism and mutuality of information obtained from the spectral characteristics of ground objects transmitted through the atmosphere to the sensors.The relationship is the fundamental work for the development of new sensors,the development of new methods in remote sensing technology,and the improvement of interpretation theories and methods.Therefore,this paper proposes a research on the radiation simulation process of remote sensing ground test field.Through the analysis of the interaction between the atmosphere,the scene and the sensor,the whole radiation calculation process is divided into three sub processes: the incident radiation field,the outgoing radiation field and the upward radiation field.The calculation of incident radiation field is mainly divided into direct solar radiation,diffuse sky radiation and background to target reflected radiation.Using the atmospheric parameters as the input data of the radiation calculation,the irradiance in the atmosphere is obtained through the calculation of the incident radiation filed,including three parts of the direct solar radiation,diffuse sky radiation and background to target reflected radiation.The output of the entire incident radiation field is the input of outgoing radiation field,and the output radiance is calculated with the influence of atmospheric parameters.After the upward radiation field calculation,the radiance results of the corresponding observation directions are obtained.Finally,the results of the radiation calculation of the remote sensing ground test field are applied to the remote sensing platform to provide a theoretical basis for the verification of the optical remote sensors.With the continuous increase of the complexity of remote sensing ground test field,the amount of data calculated by the scene radiation is increasing,which put forward higher requirements for the operation efficiency of the computer.However,due to the limitation of computer hardware,the efficiency of the computer can hardly be greatly improved.Parallel computing has become a new research hotspot and has great help in solving complex scenes.Therefore,the parallel computing method is adopted to improve the efficiency of radiation computation,so as to solve the problem of long computation time due to the large amount of data.The process of radiation calculation between the geometrical models in the 3D scene is relatively independent,and the process of radiation calculation between the triangular facets in the geometrical model is also relatively independent.Through comparison and analysis by parallel experiments,the parallel computing method based on Open MP and CUDA can all improve the efficiency of radiation calculation in varying degrees.Compared with pre parallel computing,the parallel computing method based on Open MP can get speedup of about 1 times.The parallel computing method based on CUDA is about 20 times of the parallel computing method based on Open MP.The experiment in this paper is based on a single GPU.Now quite a number of accelerated cards have more than one GPU,mixed programming based on MPI for data distribution and reception and based on CUDA for data computation is widely used,and it can achieve higher speedup.