本文選題：非視域成像　切入點：單光子探測　出處：《哈爾濱工業(yè)大學》2017年碩士論文　論文類型：學位論文

【摘要】：非視域激光成像技術(shù)是利用散射光攜帶的飛行時間信息對視域外的目標進行三維像重建的技術(shù)。該技術(shù)是近幾年興起的一種新型的激光成像技術(shù),在機器視覺、反恐偵查、醫(yī)學成像、歷史考古以及飛行器導航等眾多領(lǐng)域有著很強的應用前景。本文從基于橢球逆投射方法的非視域成像出發(fā),理論分析了該方法自身原因?qū)е伦罱K恢復像存在不確定區(qū)域的原因。通過仿真分析出該方法存在以下問題:成像體制單一、場景信息利用率低,橫縱向分辨率不一致以及濾波算法單一、對噪聲敏感、恢復像畸變的問題。之后本文即針對上述問題分別從成像體制和恢復算法上進行了優(yōu)化。針對逆向橢球投射方法恢復像在橫縱向分辨率不一致的問題,根據(jù)逆向橢球投射方法疊加時使用的是偏心率較大的橢球面情況,本文提出球投射恢復方法,從三維圖像頻域空間信息獲取范圍角度證明球投射方法成像質(zhì)量比橢球投射高的原因。對于單點目標,同樣系統(tǒng)設(shè)定情況下逆向橢球投射恢復像橫向半峰寬占26個體素,而逆向球投射的恢復像占12個體素。典型的雙點目標實驗結(jié)果也和理論和仿真結(jié)果一致。針對非視域激光成像在非視域場景中的信息利用率低的問題,本文提出了使用兩個互相垂直的墻面進行雙中介面的非視域激光成像的體制。首先分析兩個中介面存在時可能存在的4種成像方式,使用雙中介面各自恢復像歸一化疊加的方式進一步減少恢復像的不確定區(qū)域。仿真和實驗的結(jié)果顯示使用雙中介面進行非視域成像對提高最終恢復像的位置準確度、強度均勻性有著重要的意義。最后針對橢球投射算法恢復像存在彎曲畸變以及在噪聲存在情況下邊緣模糊的問題,本文首先引入了聚類算法中的mean shift濾波方法,仿真結(jié)果表明使用mean shift濾波方法的逆向橢球投射算法在多目標或者帶噪聲的情況下具有優(yōu)秀地聚類、抑制噪聲、邊緣保持以及保留強度低目標不被閾值掉的特點。之后從非視域激光成像的另一種恢復算法-代數(shù)迭代法出發(fā),通過最優(yōu)化方法中的梯度投影算法恢復圖像,通過建立上述算法的仿真得到的恢復像質(zhì)量優(yōu)于逆向橢球投射算法,代數(shù)迭代法在參數(shù)選取合適的情況下恢復像彎曲畸變的情況得到改善。
[Abstract]:Non-visual laser imaging technology is a 3D image reconstruction technology based on time-of-flight information carried by scattered light. It is a new laser imaging technology developed in recent years, which is used in machine vision, anti-terrorism detection. Many fields such as medical imaging, historical archaeology, aircraft navigation and so on have strong application prospects. This paper starts from the non-horizon imaging based on ellipsoidal inverse projection method. This paper theoretically analyzes the reason that the method itself leads to the uncertain region of the final restoration image. The simulation results show that the method has the following problems: the imaging system is single and the scene information utilization ratio is low. The horizontal and vertical resolution is inconsistent and the filtering algorithm is single and sensitive to noise. The problem of image restoration distortion is discussed in this paper. Then, we optimize the imaging system and restoration algorithm for the above problems, and aim at the problem that the resolution of image restoration in horizontal and vertical direction is not consistent with the reverse ellipsoidal projection method. According to the case of ellipsoidal surface with high eccentricity when the reverse ellipsoidal projection method is superimposed, a spherical projection restoration method is proposed in this paper. The reason that the imaging quality of the spherical projection method is higher than that of the ellipsoidal projection is proved from the angle of the frequency domain spatial information acquisition range of the 3D image. For a single point target, the transverse half-peak width of the reverse ellipsoidal projection restoration image accounts for 26 individual elements under the same system setting. The restoration image of reverse sphere projection accounts for 12 individual elements. The typical experimental results of two-point target are in agreement with the theoretical and simulation results. In view of the problem of low information utilization rate of non-visual laser imaging in non-visual scene, In this paper, we propose a method of using two vertical walls to carry out non-visual laser imaging with two mediating surfaces. Firstly, four imaging methods that may exist in the presence of two interfacial surfaces are analyzed. The method of normalized superposition of restoration images with double mediums is used to further reduce the uncertain regions of restoration images. The simulation and experimental results show that the use of double mediums for non-visual imaging can improve the accuracy of the final restoration images. The intensity uniformity is of great significance. Finally, aiming at the problems of bending distortion and edge blur in the restoration image of ellipsoidal projection algorithm, this paper first introduces the mean shift filtering method in clustering algorithm. The simulation results show that the inverse ellipsoidal projection algorithm using mean shift filter has excellent clustering and noise suppression in the case of multiple targets or with noise. Edge preservation and retention of low intensity targets are not lost by threshold. Then, from another restoration algorithm of non-visual laser imaging, algebraic iterative method, gradient projection algorithm in optimization method is used to restore images. The restoration image quality obtained by the simulation of the above algorithm is better than that of the reverse ellipsoid projection algorithm, and the algebraic iterative method can improve the image bending distortion when the parameters are selected properly.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN249

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