Simulation of infrared thermal image through atmospheric transmission

It is important to study atmospheric transmissioin for infrared imaging and object recogni-tion.On the assumption that the surface is diffusion gray-body,and the temperature difference can be ignored in air path,a numerical expression is derived for atmospheric transmission.On this basis,the feasibility of replacing object′s spectral radiance with equivalent black-body′s spectral radiance in atmos-pheric transmission computation is analyzed.The results show that in atmospheric transmission computation of 8-12 μm,object′s spectral radiance can be treated as its equivalent black-body′s spectral radiance with enough precision,which may reduce the load of computation greatly.While in 3-5 μm,the impact of sun radiation on objcet′s spectral radiance can not be ignored,it brings large deviation by using equivalent black-body′s spectral radiance in atmospheric transmission computation.