【作者】 程江华；

【导师】 孙即祥；

【作者基本信息】 国防科学技术大学 ， 电子科学与技术， 2013， 博士

【摘要】 道路作为重要的人造地物，是构成现代交通体系的主要部分，具有重要的地理、政治、经济、军事意义。由于合成孔径雷达(Synthetic Aperture Radar, SAR)系统具有全天时、全天侯等优点，从SAR图像中提取道路日益受到重视。高分辨率使得对地观测中更多的地物细节得到呈现。在高分辨率SAR图像中，道路不再表现为线特征，而是呈现出由亮的双边缘包围的暗长区域。然而，高分辨率也使得各类干扰得到放大，道路旁的阴影遮挡、道路上的车辆等各类干扰的存在、道路类型的多样性以及环境背景的复杂性，使得高分辨率SAR图像道路提取变得复杂而艰巨。针对当前SAR图像道路提取所存在的问题，本论文主要根据高分辨率SAR图像道路的辐射及几何特征，对高分辨率SAR图像道路交叉口的自动提取、道路自动以及半自动提取问题分别展开深入研究，提出了系列新的提取算法。在第三章高分辨率SAR图像道路交叉口自动提取研究中，提出一种直接检测识别道路交叉口的新方法。该方法先根据交叉口的灰度特征，利用形态学变换，全局搜索交叉口候选区域中心点位置；然后以此为局部窗口中心，采用多阈值Otsu分割出各个局部窗口内道路目标；接着根据交叉口的几何特征，通过矩形旋转得到角度均值图，获取与交叉口相连的道路个数，最终识别出交叉口的类型。实验结果表明该方法可有效提取出各种干扰下的交叉口目标。在第四章高分辨率SAR图像道路自动提取研究中，论文针对基于传统马尔科夫随机场(Markov random field, MRF)模型道路提取方法存在求解过程偏慢及参数设置偏多的问题，提出先根据道路空间几何特征关系对提取出的线基元进行预连接，以此减少虚假连接给MRF迭代求解带来的运算量；然后建立MRF道路网改进模型对道路网进行快速标记的方法。使用1m机载高分辨率SAR图像进行实验，结果表明该方法的有效性。在第五章高分辨率SAR图像道路半自动提取研究中，提出一种局部检测和全局跟踪相结合的道路中心点提取方法。在局部检测时，设定内外双窗口，外窗口根据护栏、绿化带等干扰物与道路的边缘呈现一致的方向性，采用非线性结构张量获取该区域内的道路方向；内窗口根据方向结果调整转向，搜索道路区域，进而确定道路的宽度及中心点。在全局跟踪阶段，为克服路上阻塞及路旁建筑物遮挡造成跟踪频繁失败的影响，采用粒子滤波器变步长跟踪的策略。实验结果表明该方法能有效降低各种干扰及遮挡物的影响，有效实现道路中心点的跟踪提取。综上所述，本论文的研究将为高分辨率SAR图像地物目标解译做有益探索，同时道路提取的应用技术研究也将为以后的工程实践提供研究思路。更多还原

【Abstract】 As the typical man-made land object, roads are essential parts of moderntransportation system, which have important geographical, political, economic andmilitary values. As a kind of microwave remote sensing system, Synthetic ApertureRadar (SAR) data acquisition could operate during both day and night, and isindependent on the influence of sunlight and clouds. Becaese of these merits, roadextraction from SAR images has attracted attentions of researchers all over the world.More land object details can be described in high-resolution SAR images compariedwith which in low-resolution images. Ideally, roads may be modeled as dark elongatedareas surrounded by pairs of parallel bright edges in high resolution SAR images.However, the successive road areas are frequently broken by obstacles and shadows,such as vehicles on the road, trees along the road, building shadows covering the road,etc. Road extraction is still a difficult task in high resolution SAR.Considering the difficulties of current road extraction methods and according to theradiate and geometric properties, the thesis lucubrates on the automatic andsemi-automatic road extraction problems respectively, and automatic road junctions’extraction problems, which can be suitable for different applications.In the research on the automatic extraction of road junctions from high resolutionSAR images, a new method is proposed for directly detecting and identifying roadjunctions. Firstly, based on the junctions gray feature, global searching is done for thecenter positions of the road junctions’ candidate regions, by using morphologicaltransformation methods. Secondly, the center positions are set as the local windowscenters, road targets are segmented by using the multi-threshold Otsu method in thelocal windows. Thirdly, according to the geometric characteristics of junctions, weobtain the angle-mean figure in the rectangular template rotation process, and then getthe number of the roads connected to a junction. Finally, the style of the junction isrecognized. In1m high-resolution airborne SAR image experiment, the results indicatethat this method is effective to detect and identify the junctions with variousinterferences.In the research on the automatic extraction of road networks from high resolutionSAR images, Markov random field (MRF) model can make full use of the imagerycontextual characters and priori knowledge, which have been widely used to extractroad networks. However, there exist some problems such as slow solution and manyparameters setting of these type methods. In order to reduce the computation ofsubsequent iterative solution of MRF, pre-linking is firstly introduced to removenumerous false line elements based on the spatial relationship among them. Then, theimproved road networks Markov function model is established to label road networks. SAR images with1meter resolution are tested in the experiment. And the results showthe effectivity of the method mentioned above in high resolution SAR imagery roadnetwork extraction.In the research on the semi-automatic extraction of road junctions from highresolution SAR images, a new road center-point extraction method is proposed bycombined using local detection and global tracking. In local detection phase, twowindows are set. The outside window is used to obtain the local road direction by usingnon-linear structure tensor, based on the fact that fences, green belts and otherdisturbances point to a consistent direction with the edge of roads. The inside windowadjusts its direction by the result of non-linear structure tensor. Then it searches for theroad areas, and determines the width and center of roads. In global tracking phase,particle filter of variable-step is used for solving the problem of tracking brokenfrequently by occlusions on the road and shadowing alongside the road. In1mhigh-resolution airborne SAR image experiment, the results indicate that this method iseffective.As mentioned above, this dissertation has explored the methods of road extractionin high-resolution SAR images. Also, these methods would be helpful to enginerringapplications posterior.更多还原