摘要：
The accurate calculation of IR emissivity is the basis of modeling and analyzing the ship turbulent trailing wake in IR. Based on Cox-Munk probability distribution function (PDF) of slopes model, and corresponding to bi-directional reflectance distribution (BRDF) function of sea surface, a method for calculating IR emissivity of ship turbulent trailing wake in typical ocean environment was formulated. According to calculation, the emissivity distribution of typical ship turbulent trailing wake in 8-9 μm long-IR band for both small zenith angle of airborne detection and big zenith angle of shipborne detection were studied. The results show that the difference of emissivity between turbulent trailing wake and sea background is increased along with the detecting zenith angle. What's more, the radiance of turbulent trailing wake of typical ship is calculated in cloudy autumn shipborne detection condition, which is compared with the sea trial data. The results show that in typical ocean condition, the radiance of turbulent trailing wake is lower than sea background, presenting the characteristic of "cold trailing wake".%紅外發(fā)射率的準(zhǔn)確計算是艦船湍流尾跡紅外仿真與特性分析的基礎(chǔ).文中以湍流尾跡對Cox-Munk海面坡度概率密度分布的調(diào)制模型為基礎(chǔ),結(jié)合海面雙向反射分布函數(shù),研究了典型環(huán)境下艦船湍流尾跡海面紅外發(fā)射率的計算方法;研究了機載小天頂角、船載大天頂角觀測時,艦船湍流尾跡長波8~9 μm紅外發(fā)射率的分布規(guī)律,得到了湍流尾跡與海面背景發(fā)射率的差別隨觀測天頂角的增大而增大的結(jié)論;仿真計算得到了秋季陰天船載式探測條件下,典型艦船湍流尾跡的紅外輻射亮度,并與海上試驗數(shù)據(jù)進行了對比,結(jié)果表明湍流尾跡的自發(fā)輻射亮度低于海面背景,表現(xiàn)為"冷尾跡"的特征.
摘要：
Based on infrared physics fundamentals and natural scene simulation theories, we proposed an im-proved system for infrared scene simulating to fulfill the real-time and accuracy requirements. Firstly, we dis-cussed and improved zero-range-distance infrared radiation and temperature field calculation models. We re-formed the empirical formulations by considering the declination of the Sun to improve the accuracy of our com-putation. Secondly, after we discussed the problems of positioning the heat resource and computing the heat transmission, we incorporated and took account of infrared features of different physical materials to generate high-quality rendering effects. Lastly, we used GPU to accelerate the computation for infrared emission gradation of multiple objects in various scenes. Our system is based on Unity3D and it can construct many infrared scenes consisting of multiple objects, for instance, plants, buildings and vehicles. The comparisons of our simulation re-sults with the authentic infrared images show the effectiveness of our system. Additionally the rendering speed of 30 frames per second can meet most basic real-time computational requirements.%基于紅外物理基礎(chǔ)理論和自然場景仿真理論. 通過改進已有算法以滿足紅外仿真系統(tǒng)中的實時性和準(zhǔn)確性2個基本要求. 提出基于Unity3D的改進實時紅外仿真系統(tǒng). 首先探討并修正了部分零視距離輻射計算模型和影響溫度場的主要計算模型, 在計算中考慮太陽赤緯角, 改進經(jīng)驗公式, 提高了計算的準(zhǔn)確性; 然后在討論了熱源放置和熱傳遞計算問題之后. 在紅外仿真中考慮物體不同材質(zhì)特性對紅外效果的影響. 使得繪制結(jié)果更為逼真; 最后借助GPU 對不同場景對象多角度下的紅外輻射灰度進行并行計算. 提升計算速度. 該系統(tǒng)基于 Unity3D 游戲引擎. 可以構(gòu)建包含多種目標(biāo)對象的紅外場景, 如植被、建筑以及車輛; 重建的三維場景仿真效果圖與實地拍攝的真實紅外場景圖像高度相似. 仿真實驗渲染速度達到30幀/s, 基本滿足實時性計算要求.
摘要：
紅外仿真圖像的真實度決定仿真圖像的價值,提高仿真圖像逼真度有重要的意義.通過對影響仿真真實度的因素進行分析,從探測器原理和建模精細(xì)度等方面構(gòu)建了相應(yīng)的仿真模型,增加仿真圖像的真實感.根據(jù)探測器的量化原理,提出了增益控制仿真模型,提高圖像的量化質(zhì)量;采用可見光紋理信號調(diào)制紅外能量,增加圖像的紋理細(xì)節(jié).與原方法和真實圖像的實驗對比結(jié)果表明,這些模型能夠有效地提高仿真圖像的質(zhì)量,更具有真實感.%The fidelity of synthetic infrared image determines the value of simulation system,research on the mthod of improv-ing synthetic image fidelity is important.By analyzing the factors that affect the fidelity,the corresponding simulation model is con-structed to improve fidelity of synthetic image based on the principle of infrared detector and modeling precision.A gain control mod-el is proposed to improve the quantification quality according to the principle of the infrared detector,using visible light texture sig-nal to modulate the infrared energy to increase the texture details.Compared with the original method and real image,experiments show that these methods can effectively improve the fidelity of the synthetic infrared image.
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