| The optical detection and recognition technology of dim air target is one of the most important development directions in the fields of military aerospace and national defense security.For space-based optical detection,the detection scene is complex,including not only the target and background,but also high-reflection cloud layer,ground high-temperature heat source and airborne lightning and other false alarm sources,which will seriously affect the detection and recognition probability of the target.Based on the space-based optical detection mechanism,this paper analyzes the potential false alarm source and conducts characteristic research and modeling simulation to support the research of detection load design and detection identification algorithm.The specific research content is carried out:(1)Based on the detection scheme of the space-based optical detection system,the principle of the threshold detection algorithm is analyzed,and the potential false alarm sources are calculated and analyzed under different detection scales(including time scale,spatial scale and radiation scale).First,the pixel size of the target and the false alarm source and the pixel speed on the image plane are calculated based on the optical imaging model;Then,calculate the radiation characteristics of the target and the potential false alarm source;Finally,based on the analysis of the calculated data,the sources of false alarms at each scale are given.(2)The infrared radiation characteristics of high reflectivity clouds are studied and a simulation model is established.First,analyze the physical mechanism of cloud optical imaging,the radiant energy transmission process of light incident,absorption,and scattering;Then,using the Mie scattering theory and combining the concentration and particle size distribution of the cloud particles to obtain the spectral radiation characteristic parameters of the cloud particle system;Then,the radiation characteristics of the cloud layer are modeled and calculated;Finally,the Dimond Square fractal algorithm is used to generate the shape structure of the cloud layer,and the radiance of the cloud layer under the corresponding shape structure is calculated and converted into the image DN value to generate an infrared simulation image of the high reflectivity cloud layer.(3)The infrared radiation characteristics of the ground high temperature heat source were studied and a simulation model was established.Firstly,based on the realtime high-temperature heat source remote sensing image,the original image is subjected to radiation calibration and atmospheric correction to obtain the radiance of the heat source;Then,based on the physical imaging mechanism,the ground high temperature heat source temperature inversion model is established to invert the temperature distribution characteristic parameters of the heat source;Then,calculating the radiance of the corresponding pixel under different simulation conditions;Finally,the calculated infrared radiance value of each pixel is converted into the image DN value to generate an infrared simulation image of the ground high temperature heat source.(4)The infrared radiation characteristics of lightning in the air were studied and a simulation model was established.Firstly,combined with the physical properties of lightning,the fractal L-System algorithm is used to simulate the shape and structure of lightning;Then,according to the LIS data of the existing airborne lightning,the shortwave infrared and medium-wave infrared lightning radiation are modeled and calculated respectively;Then,the shape structure of the lightning is combined with the calculated radiance to form a preliminary lightning infrared simulation image;Finally,the simulation of the radiation transmission imaging process,the atmospheric point spread function is introduced into the simulation of the lightning infrared image,the halo effect of the lightning is simulated,and the lightning infrared simulation image is generated. |
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