Research On Fast Calculation And Simulation Of Atmospheric Radiation Transfer

Atmospheric radiation transfer is based on the theory of electromagnetic propagation,thermodynamics and molecular spectroscopy.It mainly studies the transfer and conversion of radiation energy in the atmosphere.Atmospheric effect simulation is a visual display of the numerical results of atmospheric radiation transfer.Atmospheric effect simulation is of great significance in engineering application.From digital earth to small-scale scene simulation,atmospheric radiation transfer effect has a vital impact on the fidelity of the scene.Most of the current mainstream atmospheric radiation transfer models have the advantages of high spectral resolution and high reliability of calculation results,but the calculation speed is relatively slow.For some atmospheric radiation transfer calculations with low spectral resolution,the use of a simpler and faster calculation model can improve the calculation efficiency.In this paper,fast calculation and real-time simulation of atmospheric radiation transfer are taken as the research objectives,and the following work has been done:(1)Based on Rayleigh scattering,Mie scattering and gas absorption theory,the influence of atmospheric pressure and temperature on gas absorption coefficient is considered.The absorption coefficient is modified by empirical formula,and the atmospheric transmittance is calculated by Lambert-Beer law.Based on Kirchhoff's law,a simplified calculation method of atmospheric self-radiation under local thermodynamic equilibrium is studied.Considering the scattering effect of atmosphere on sunlight,a simplified calculation model of atmospheric scattering is used to calculate the atmospheric scattering brightness by successive scattering superposition method.(2)Considering the characteristics of atmospheric spherical distribution,this paper studied the stratification method and geometric parameter calculation method of spherical atmosphere,and the high-speed calculation of atmospheric radiation transmission is realized by GPU.In order to meet the requirements of real-time simulation of atmospheric radiation transmission,a mapping method of atmospheric transmittance,atmospheric path radiation and scattering look-up tables is studied in this paper.This mapping method can be applied to atmospheric effect simulation of spherical atmosphere.In order to reduce the precision loss caused by linear interpolation in atmospheric texture sampling,a non-linear texture mapping method is used in this paper.(3)Comparing the results of this model with those of MODTRAN,this paper analyzed the feasibility of the simplified algorithm.The calculation method of equivalent texture and the calculation method of atmospheric geometric parameters under different observation modes are also studied,thus realizing the real-time simulation of atmospheric effects based on texture mapping functions.