Research Of Modeling And Simulation Techniques Of Atmosphere And Clouds Three-Dimensional Radiometric Scene

Atmosphere and clouds are the main background source of space-based infrared target detection system, how to simulate radiometric images of atmosphere and clouds scenes effectively and authentically is an important research direction at home and abroad, which can affect the validity of the results from simulation experiments in space-based infrared target detection systems.In this dissertation we start with modeling the three-dimensional spatial structure of clouds using the rescale-and-add (RSA) fractal algorithm, different types of clouds and dynamic clouds can be modeled by controlling the parameters of this algorithm , the distribution and internal micro-physical structure of atmosphere and clouds have been studied simultaneous as a guideline for modeling. By integrating Mie scattering theory with scattering property database of nonspherical ice particles, we have worked out the optical property of atmosphere and clouds, on the basis of which the three-dimensional radiometric scene of the modeled atmosphere and clouds have been figured out using spherical harmonic discrete ordinate method (SHDOM) which is one of the most popular model for the calculation of radiative transfer function.During the study on SHDOM, we propose a new composite optimization algorithm for k-interval parameters by setting the threshold, which obviously improve the speed of SHDOM for broadband calculation without decreasing the accuracy. Furthermore, we have designed a module as a supplement of SHDOM for generating surface boundary conditions which brings the geographic environmental factors referred to the global land cover characterization database and spectral database of various materials.In the last section, radiometric images have been obtained by projecting the three-dimensional radiometric scene with several observation angles and objectives can be locating in the image plane. Imaging chain has been simulated, through which we finally get the emulated radiometric images of atmosphere and clouds, and successfully complete the whole simulation system.The mixed programming using Fortran, Visual C + + and Matlab language has been applied to the implementation of this simulation system, it has already been used in the simulation experiments of missile early warning system in medium /low earth orbit and revised constantly during the practical application.