Space Based Infrared Imaging System Simulation Based On Ray Tracing

With the rapid development of various space weapon technologies,the space environment is becoming more and more complex,and the efficient and accurate continuous detection and locating of these space weapons has become an important strategic goal of space-based infrared early warning systems in various countries.However,the space-based infrared system platform has long development cycle,high experimental cost and needs a lot of data support.Computer simulation can provide abundant reference data under various conditions,shorten the equipment development cycle and save costs.In order to obtain credible simulation data,it is necessary to establish detailed physical models and adopt accurate simulation methods.In this thesis,a global-scale 3D background radiation field and target radiation model are established based on the measured data of remote sensing for spacebased infrared scenes,in terms of simulation method,ray tracing algorithm is used to fully calculate the coupling effect of infrared radiation emitted by all objects in the scene,so as to achieve high realistic rendering of space-based infrared radiation field.The main research contents of this thesis are as follows:Firstly,the rendering process of ray tracing method is studied.The physical advantages of ray tracing method in infrared simulation are discussed in this thesis,deduced the calculation method of ray intersecting with different geometric primitives,analyzed the BVH tree hierarchical bounding structure to accelerate the intersection test,and the path integral calculation model in ray iteration process by combining with Monte Carlo integral method is drived.Secondly,an accurate model of space-based infrared radiation imaging chain with multielement coupling on a global scale is established.The surface background is divided into land and ocean separately,and the surface radiation texture is designed based on the remote sensing measured emissivity,temperature and elevation data,and the uneven BRDF model of the surface and the ocean is studied.Based on the cloud data retrieved from remote sensing,the cloud top physical material model and the scattering model to the incident light are established.The atmospheric transmittance and limb path radiation at different heights and zenith angles are calculated.The self-radiation of the boost and skin of the middle phase missile are modeled,and the BRDF characteristics of the skin are analyzed using the fiveparameter model.Finally,a space-based infrared early warning ray tracing simulation system is built,and the rendered images of the earth background and missile target attack and defense process under different conditions are simulated and analyzed.According to the physical model of global3 D radiation field,ray tracing parallel rendering is realized by using C++ language.Through the iterative ray tracing integral,the high realistic rendering results of spectral radiation under the coupling effect of complex environment factors such as sun,surface,cloud and atmosphere are simulated,and the image rendering quality with different sampling complexity is compared.In order to solve the problem of target detection,a sampling calculation scheme for the infrared dim-small targets is proposed,and the early warning detection process and target signal-to-clutter ratio of the bosst and middle phase of the missile are simulated and analyzed.