Study On Realistic Real-time Infrared Scene Simulation

Scene simulation for infrared bands involves with targets and backgrounds generation in order to represent the radiance profile as a real infrared imaging system. The virtual simulation technique is an important aspect for both military and civil usages; it has the features including robustness, receptiveness, no restrictions on the weather and location, and flexible design, which can reduce the research risks and the time to save the experimental expenses. With the rapid developing of personal computers and graphics hardware, it is possible to simulate the complex scene in real time. Therefore, it has attracted a lot of interests for researchers to improve the performance and lifelike profile for each module in the GPU-based scene simulation software system.In order to construct a suite of infrared scene simulation software based on physical principles in real time, this paper focus on the general framework, infrared texture generation, radiation feature rendering and atmospheric effects, the following works have been done in this paper:The first part illustrates the GPU framework of the real-time infrared scene simulation software.By analyzing the similarity theory of infrared scene synthesis, the link of infrared composite system, and the framework characteristics, modular composition and scene synthesis process of the abroad typical infrared scene simulation software, to conclude that real-time infrared scene simulation framework design criterion should be observed: modular, hierarchical, systematic and real-time optimization. According to the design criterion, the framework of real-time infrared scene simulation and sub-modules design were completed. The modules have low coupling and high cohesion characteristics, easy to expand and modify; the task hierarchy is divided into three layer structure: “Data Management- Modeling and Scene Design- Image Generation”, and has stable data interface, convenient communication of each layer; the imaging link has been simulated, to achieve the designation of “Target – Background – Atmospheric – Imaging system” composite system; the physics-based modules has been modeled to guarantee the credible of computation; building the 3D infrared scene rendering engine on the basis of high-level render engine, improved stability, reducing the difficulty of developing. The establishment of hardware-in-the-loop testing system of infraredseeker shows the framework is availability.The second part is on method of realistic infrared texture generation. According to the theory of infrared radiation, the infrared physical texture format used in the GPU framework of the real-time infrared scene simulation was designed. Analyses the advantages and disadvantages of the target infrared texture generation method based on measurement data and digital simulation, an idea of combination of measure data and retrieval model to generate accurate, natural, rich details of object surface temperature field distribution is put forward, by combining flexible 3D rendering technique, a realistic infrared image generation method of target is found. Analyses the disadvantages of the large-scale terrain infrared texture generation method based on measurement data and artificial design, and a large-scale terrain infrared texture generation method based on visible remote sensing image is proposed. Firstly, accurate and regional distribution of natural terrain material is segmented using the VIS band image; secondly, several physics-based modulation in detail temperature distribution according the change of VIS band optical properties, elevation and adjacent domains were realized. The 3D terrain simulation experimental shows that the method is efficient and practical.The third part is on the method of radiometric rendering for complex scene. Firstly, aiming at the problem that spectrum and space integration of the spectral intrinsic radiometric equation leads to time-consuming, the article makes clear the simplified conditions of equation, achieves a primer infrared local illumination model, and realizes infrared local illumination model optimization through beforehand evaluation of radiometric characteristics for different schemes. Secondly, GPU based physical quantity look-up table method is presented based on the problem of the time consuming in direct calculation of radiometric equation physical qualities. Finally, according to the independence of equation calculation of each pixel, concurrent computation of radiometric equation according dynamic evaluation of radiometric characteristics is achived. Comprehensively applying the three types of real-time optimization methods can efficiently achieve the the precise and real-time radiation calculation for complex scene.The fourth part is on the method of high-precision real-time simulation of infrared atmospheric transmission effect. Firstly, the error calculation of average attenuation of variousradiators of different wave bands is studied. Secondly, the spectrum coupling thermal emission and reflected radiations in the spectral radiometric equation are decomposed into physical quantities, and the spectral radiometric equation is improved to become a simpler calculation between "primer" radiance terms and effective average factors. Thirdly, the data size and data dimensionality restriction problems of GPU look-up-tables of high dimensional physical quantities(atmospheric transmittance, effective average factors, etc.) is resolved, by methods of non-equidistance sampling for index parameters and function fitting of physical qualities. Finally, concurrent computation of atmospheric transmission is achieved with GPU and the precise, real-time and universal simulation infrared atmospheric transmission effect is realized.