Modeling Of Infrared Radiation Atmospheric Transmission From Sea Surface And Simulation Of Infrared Imaging System

Widely applied in both military and civil fields,infrared image(IRI)simulation technique works well in generating infrared images under various settings such as the forest,city and ocean.Enjoying advantages of low development costs,short development circles and high efficiency,sea surface IRI simulation is of great significance in constructing target detection algorithms to recognize targets above or below sea surface.As a result,sea surface IRI simulation has become an indispensable part of maintaining marine safety.This paper aims to study sea surface IRI simulation under different meteorological conditions.In this paper,Matlab was used to build up the atmospheric transmission model of sea surface infrared radiation.Then the pathways of photons in the atmosphere were simulated,and a simulation algorithm of IRI system was designed to generated sea surface IRI.This paper consists of three parts: establishing the atmospheric transmission model,simulating atmospheric point spread function(PSF),and developing the IRI simulation system.First,an atmospheric attenuation model of infrared radiation was established through atmospheric spectral transmittance table and Kim model,to calculate the transmittance of infrared radiation.By adding the direct radiation density model of the sun into consideration,the atmospheric transfer model was completed to generate the infrared radiation field from sea surface.Also,taking the collisions between photons and neutron as well as aerosol particles into consideration,PSF was estimated with Monte Carlo method(MC)and artificial neural network(ANN).The function performs convolution to the radiation field of infrared radiation from sea surface,whose result serves as the input of IRI system.Furthermore,modulation transfer function(MTF)was designed to describe the influence of the optical system,detector,and electronic circuit on the final imaging quality.Specifically,the product of three sub-system functions results in the overall MTF,as used to simulate the imaging effect of the IRI system.Considering all the above factors from the formation of infrared radiation field to back-end image generation,an intact system of sea surface IRI simulation system is proposed and simulated images are generated.As indicated in the experiments,the established atmospheric transfer model guarantees that the error of atmospheric transmittance is within 20%,compared to actual measurement.It is noticed that after atmospheric transmission,the infrared images on the sea surface remarkably become darker,with lower contrast.After training,ANN shows great advantages over MC on prediction time,with similar accuracy,better ensuring the real-time requirement of the system.Also it is concluded that optical system,detector,and electronic circuit can be viewed as low-pass filter,resulting in loss of high-frequency information.In addition,vignetting effects of optical systems will cause images to be brighter in the center,but darker on the edges.