Research On Accurate Prediction Modeling And Simulation Technology For Full-chain Multi-spectral Imaging Features Of Aerospace Targets

The aerospace targets have the following characteristics: high-speed maneuver,strategic deep penetration and long-range precision strike.Building wide-area,high-efficiency,accurate detection and continuous monitoring for aerospace targets has become a new challenge for space situational awareness.Based on the optical detection requirements for continuous monitoring of aerospace targets in a large area,the research goal of the thesis is the realization of accurate prediction modeling and application of the full-chain multispectral imaging features of aerospace targets.The upward spectral radiation field distribution of the background under various environmental conditions based on the FY-2G infrared remote sensing data is innovatively proposed.Combining the relative position relationship between the aerospace target and the cloud,a deduction model of the radiation characteristics of the aerospace target under the space-based observation before the entrance pupil of the optical system is established.On the basis of comprehensive consideration of the digital imaging signal conversion characteristics of sub-pixel targets,an accurate prediction model for the on-orbit imaging characteristics of aerospace targets based on the full chain model drive and information element coupling is constructed.Details are as follows:(1)The main factors affecting the on-orbit multi-spectral imaging characteristics of the full chain of aerospace targets are analyzed.Based on the full chain multi-spectral imaging characteristic mechanism of aerospace targets in complex environments,firstly,several major factors affecting the on-orbit imaging characteristics of the target are analyzed from the aspects of target and background spectral radiation characteristics,the working principle and modes of the infrared imaging system in geosynchronous orbit and the performance parameters coupling.Secondly,combined with the coupling mechanism of environment and aerospace targets,the pre-selected bands for the spectrum detection of aerospace targets are analyzed.Finally,the full chain multi-spectral imaging relationship of coupling of the target,background,transmission path,space-based platform and payload is comprehensively considered,and the simulation technology of aerospace target imaging feature is analyzed,which lays a theoretical foundation for the simulation and analysis of the imaging characteristics of aerospace targets.(2)Aiming at the problem of low accuracy in radiation characteristics modeling of aerospace targets,the inversion-deduction methods are used to achieve accurate modeling of the upward spectral radiation characteristics of aerospace targets based on the measured data.The upward spectral radiation intensity of the aerospace target at different heights and observation angles in front of the entrance pupil of the optical system is calculated,which provides a reliable data basis for the subsequent establishment of the target accurate imaging feature model in geosynchronous orbit.Through the analysis of the plume characteristics of the aerospace target and combining the three positional relationships between the target and the clouds,such as: the target is under the cloud bottom,in the cloud,and on the cloud top,the target radiation transmission characteristics of aircraft and missile plume are deduced.(3)Aiming at the problem of low authenticity of traditional complex background radiation characteristics modeling,this paper innovatively proposes a comprehensive modeling method for the coupling characteristics of the complex sea-cloud background upward radiation using FY-2G remote sensing data and measured data.Firstly,in order to establish a more realistic sea surface infrared radiation model,the sea surface emissivity and bidirectional reflectivity calculation methods based on measured data are respectively proposed according to the projection imaging of beam propagation and the sea surface radiation transmission model during the night and day.Secondly,the distribution of sea surface temperature and cloud top temperature in a certain area of the South China Sea is retrieved using FY-2G remote sensing data.The modeling of the background radiation characteristics of different cloud types is emphatically discussed combining the cloud classification data and the cloud phase function.Finally,a sea-cloud coupling radiation transmission model matching the sampling of space-based detectors is proposed combining the radiation coupling relationship among sea surface,cloud and atmospheric environment.This model is convenient to derive the background radiation field distribution under various environmental conditions.(4)Aiming at the problem that the coupling effect between PSF of the optical system and the sampling of the detector affects the on-orbit imaging characteristics of the target,the space imaging and energy transmission signal conversion model of aerospace targets is established based on the principle of full chain infrared imaging of sub-pixel targets.Combining the optical radiation characteristic model of aerospace targets affected by the complex environment,the spectral radiation characteristic model at the entrance pupil of the space-based sensor of the digital full chain including target plume-sea/cloud backgroundenvironmental atmosphere-optical system-imaging detector is informed.The optimal coupling condition of the PSF to the spatial resolution is analyzed.The on-orbit multispectral imaging characteristics of aerospace targets under different spectrums,backgrounds,regions,seasons,and observation conditions are simulated when PSF of the optical system best matches sampling of the detector.The above-mentioned research work provides theoretical basis and data support for the detection efficiency analysis and system parameter design of early warning satellites in high-orbit.(5)Aiming at the problem that the detection of weak targets in static images under complex background clutter is difficult,the simulation and application of the dynamic imaging feature prediction of aerospace targets under the complex earth background is studied.Combining target motion characteristics,sub-pixel target imaging signal characteristics,etc.,spacebased optical detection simulation platform is developed,and the sequence simulation of aerospace moving target imaging characteristic is realized with OSG rendering engine as the platform based on the digital full chain spectral radiation.The image complexity evaluation factor is introduced to qualitatively evaluate the detectability of the target under the complexity of a certain image sequence.This research work provides data support for intelligent algorithms for the detection and tracking of aerospace targets under the spacebased platform.