利用邻域质心投票从分类后影像提取道路中心线

目的 利用分类算法对高分辨率影像中的道路进行分割时,得到的二值图像往往混杂了许多非道路区域,且道路区域呈面状,无法直接应用于生产与研究。针对该问题,提出一种利用邻域质心投票提取道路中心线的算法。方法 首先检测像素在各方向上的连通距离以构建邻域多边形,随后进行质心投票来提取道路的中心线,与此同时估算道路宽度并判断出连通距离较长的方向数目,以排除非道路区域的干扰,最后经形态学处理得到细化的中心线。结果 选取测试图像及具有不同道路分布特征的高分辨率航空影像的分类结果进行实验,并将该算法与Zhang和Couloigner提出的算法进行了对比分析。结果显示,该算法的提取质量为80.6%和79.0%,且计算效率较高,处理实际影像的用时小于参考算法的20%,此外在稳定性及对不同路宽的适应性等多个方面均具有优势。结论 提出一种邻域质心投票算法,该算法能够同时实现传统方法中提纯与中心线提取两个步骤所对应的功能,从分类影像直接提取道路中心线。实验结果表明,该算法能够根据形状特征有效检测道路,且具备一定抗干扰能力,适用于对混杂了非道路区域的高分辨率影像的分类结果进行处理。     

A two-stage framework for road extraction from high-resolution satellite images by using prominent features of impervious surfaces

The segmentation and classification of high-resolution satellite images (HRSI) are useful approaches to extract information. In recent times, roads and buildings have been classified for analysis of urban areas in a better manner. Apart from these, healthy trees are also an important factor in HRSI, i.e. adjacent to roads, and vegetation. They reflect the area in an image as land cover. Other important information, shadow, is extracted from satellite images, which indicates the presence of trees and built-up areas such as buildings, flyovers, etc. In this article, a weighted membership-function-based fuzzy c-means with spatial constraints (WMFCSC) approach for automated satellite image classification is proposed. Initially, spatially fuzzy clustering is used to classify the satellite images in healthy trees with vegetation, roads, and shadows, which includes the information of spatial constraints. The road results of the classified image are still having non-road segments. Therefore, the proposed four intermediate stages (IS) are used to extract the road information, followed by the results of road areas of the WMFCSC approach. The framework of IS helps to remove the false road segments which are adjacent to roads and renovates the segmented roads due to the shadow effect. A final step of a hybrid WMFCSC-IS approach is used to extract the road network. The results of classified images confirm the effectiveness of the WMFCSC-IS approach for satellite image classification.     

基于PPMU-net的多特征高分辨率遥感道路提取

针对复杂地形条件下道路特征选取不具代表性,分割精度低的问题,提出了一种基于卷积神经网络（PPMU-net）的高分辨率遥感道路提取的方法。将3通道的高分二号光谱信息与相应的地形信息（坡度、坡向、数字高程信息）进行多特征融合,合成6通道的遥感图像;对多特征的遥感图像进行切割并利用卷积网络（CNN）筛选出含道路的图像;将只含道路的遥感图像送进PPMU-net中训练,构建出高分辨率遥感图像道路提取模型。在与U-net神经网络、PSPnet神经网络相比时,所提的方法在对高分辨率遥感道路提取时能够达到较好的效果,提高了复杂地形条件下道路分割的精度。     

Automatic Road Extraction from Aerial Images

The paper presents a knowledge-based method for automatic road extraction from aerial photography and high-resolution remotely sensed images. The method is based on Marr's theory of vision, which consists of low-level image processing for edge detection and linking, mid-level processing for the formation of road structure, and high-level processing for the recognition of roads. It uses a combined control strategy in which hypotheses are generated in a bottom-up mode and a top-down process is applied to predict the missing road segments. To describe road structures a generalized antiparallel pair is proposed. The hypotheses of road segments are generated based on the knowledge of their geometric and radiometric properties, which are expressed as rules in Prolog. They are verified using part–whole relationships between roads in high-resolution images and roads in low-resolution images and spatial relationships between verified road segments. Some results are presented in this paper.     

光谱与形状特征相结合的道路提取方法研究

针对从遥感影像上提取道路,目前已经有很多研究,但尚有许多问题有待解决。如果仅从光谱特征分类入手提取道路,会存在“异物同谱”问题。为解决这个问题,提出了用光谱特征与形状特征相结合的方法提取道路。提出了3个形状指数描述道路的形状特征。以SPOT卫星影像为例,将高空间分辨率的全色图像与多光谱图像融合,首先基于道路光谱特征进行图像分类,然后再应用道路的形状特征去除分类图像中的“异物”目标。研究结果表明该方法能有效地从遥感影像中提取主干道路。     

一种高分辨率遥感影像道路信息提取方法

道路在国民经济建设和国防建设中发挥着重大的作用,是非常重要的基础地理信息,一直以来研究道路的自动或半自动提取都被视为热点和难点,提出的理论和方法层出不穷,但没有一种方法能推广应用。针对道路难以从高分辨率遥感影像中提取的问题,提出了一种道路提取方法,首先影像将RGB颜色空间转换成HSV颜色空间,运用改进的区域分隔算法,实现道路区域的分隔。然后利用数学形态学腐蚀、膨胀等基本运算,结合区域的形态特征(如面积、紧凑度等)实现道路与非道路信息的分离。对多幅复杂道路图像进行试验,结果表明本方法能够很好地实现从复杂环境中提取道路信息。     

Use of colour transformation and the geodesic method for road centreline extraction from VHR satellite images

Seed point-based road extraction methods are vital for extracting road networks from satellite images. Despite its effectiveness, roads in very high-resolution (VHR) satellite images are complicated, such as road occlusion and material change. To tackle this issue, this paper proposes to use the colour space transformation and geodesic method. First, the test image is converted from Red-Green-Blue colour space to Hue-Saturation-Value colour space to reduce the material change influence. The geodesic method is subsequently applied to extract initial road segments that link road seed points provided by users. At last, the initial result is adjusted by a kernel density estimation method to produce centred roads. The presented method is quantitatively evaluated on three test images. Experiments show that the proposed method yields a substantial improvement over cutting-edge technologies. The findings in this study shine new light on a practical solution for road extraction from satellite images.     

Automatic finding of main roads in aerial images by usinggeometric-stochastic models and estimation

This paper presents an automated approach to finding main roads in aerial images. The approach is to build geometric-probabilistic models for road image generation. We use Gibbs distributions. Then, given an image, roads are found by MAP (maximum a posteriori probability) estimation. The MAP estimation is handled by partitioning an image into windows, realizing the estimation in each window through the use of dynamic programming, and then, starting with the windows containing high confidence estimates, using dynamic programming again to obtain optimal global estimates of the roads present. The approach is model-based from the outset and is completely different than those appearing in the published literature. It produces two boundaries for each road, or four boundaries when a mid-road barrier is present     

Three-Dimensional Image Reconstruction Procedure for Food Microstructure Evaluation

Confocal laser scanning microscopy (CLSM) is a noninvasive technique for evaluating the microstructure of foods and other materials. CLSM provides several sequential subsurface layers of two-dimensional (2-D) images. An image processing algorithm was developed to reconstruct these 2-D layers into a three-dimensional (3-D) network. Microstructure of fat globules in cheese was used as an example application. The validity of the image reconstruction algorithm was evaluated by processing several layered digital images of known shape and size. Differences between the original and reconstructed images were 2–5% in terms of object size and 1–8% in terms of shape.     

基于视觉显著性特征的遥感影像道路网提取方法

在遥感影像上,道路被认为是颜色、纹理、形状相似的狭长线状目标,基于此特征可知,整个道路网在影像上会呈现非常显著的特征,极易引起人眼的注意,我们称之为感兴趣区域。感兴趣区域是场景中最能引起用户兴趣、体现图像主要内容的区域,视觉认知理论的研究表明：通过视觉注意机制可以模拟人眼的观察过程,找出遥感影像上的显著区域。本文提出应用视觉注意机制辅助遥感影像道路网提取的思想,通过对影像的显著区域进行分析和处理,得到最终的道路网。对比实验表明该算法可以有效的提高道路网提取的准确率和完整性。     

一种新的高分辨率SAR图像道路提取算法

针对高分辨率SAR图像中道路目标难以有效提取的问题,提出一种新的高分辨率SAR图像道路提取算法,它结合了参数化内核图割和数学形态学算法。利用参数化内核图割对高分辨率SAR图像中的道路目标进行初级分割,用数学形态学填充空洞,平滑道路边缘;基于道路的几何特征,使用矩阵度、改进的长宽比、复杂度等因子去除虚警;针对处理过程中出现的道路断裂情况,利用数学形态学提取道路目标的中心线,同时根据线段邻近性、方向一致性准则对其断裂部分进行连接,用数学形态学还原道路宽度,得到道路提取结果。实验结果表明该算法不用进行SAR图像预处理,也可以有效抑制相干斑噪声,并且能准确、较为完整地提取道路目标。     

Road Detection and Tracking from Aerial Desert Imagery

We present a fast, robust road detection and tracking algorithm for aerial images taken from an Unmanned Aerial Vehicle. A histogram-based adaptive threshold algorithm is used to detect possible road regions in an image. A probabilistic hough transform based line segment detection combined with a clustering method is implemented to further extract the road. The proposed algorithm has been extensively tested on desert images obtained using an Unmanned Aerial Vehicle. Our results indicate that we are able to successfully and accurately detect roads in 96% of the images. We experimentally validated our algorithm on over a thousand aerial images obtained using our UAV. These images consist of straight and curved roads in various conditions with significant changes in lighting and intensity. We have also developed a road-tracking algorithm that searches a local rectangular area in successive images. Initial results are presented that shows the efficacy and the robustness of this algorithm. Using this road tracking algorithm we are able to further improve the road detection and achieve a 98% accuracy.     

彩色公路交通地图图像道路提取

根据彩色公路交通地图的图像特征,提出一种新颖的道路识别与提取方法。这种方法包括三个关键步骤。首先,根据区域的特征,提取出区域的灰度值;其次,根据道路的颜色和形状特征以及数字图像处理的一些方法（如对象的连通成分等）,识别并提取出道路的颜色;最后,为了获得完整的道路网络,一些道路连接方法被提出。这种算法已经被应用于许多彩色公路地图图像中去提取道路网络。大量成功的实例表明这个算法是非常有效的。     

结合非监督分类和几何—纹理—光谱特征的高分影像道路提取

目的 目前针对复杂场景高分辨率遥感影像道路提取多采用监督分类方法,但需要人工选择样本,自动化程度低且具有不稳定性。基于像元级的方法,提取完整度低且易产生椒盐噪声;面向对象的方法易产生粘连问题。为了提高道路提取的完整度、准确度和自动化程度,提出一种基于非监督分类和几何—纹理—光谱特征的道路提取方法。方法 首先考虑光谱特征利用非监督分类进行初步分割,结合基于纹理特征分类的结果得到初始道路区域。然后根据道路特征建立一套完整的非道路区域滤除体系：边缘滤波断开道路和非道路的连接、纹理滤波滤除大面积非道路区域、形状滤波去除剩余小面积非道路区域。最后利用张量投票算法得到连贯、平滑的道路中心线。结果 选择复杂场景下的高分辨率IKONOS影像和QuickBird影像进行实验,与国内外基于像素和面向对象的两种有代表性的道路提取方法进行对比,采用完整率、正确率、检测质量3个评价指标进行定量评价。实验结果表明该方法相比于其他算法在完整率、正确率和检测质量上平均提高26.61%、5.57%和26.77%。定性分析结果表明,本文方法可以有效改善椒盐噪声和粘连现象。此外本文方法的自动化程度更高。结论 提出了一种基于非监督分类和几何—纹理—光谱特征的高分辨遥感影像道路提取方法,非监督相对于监督分类的方法有更高的自动化程度,复杂场景下的道路提取融合几何—纹理—光谱特征有效避免了基于像元级道路提取易产生的椒盐噪声现象和面向对象道路提取易产生的粘连现象。该方法适用于高分辨率遥感影像城市道路提取,能够得到较高的完整度、准确度以及自动化程度。非监督分类和多特征结合的道路提取方法有广阔的应用前景。     

Automatic comparison of a topographic map with remotely sensed images in a map updating perspective: The road network case

A map guided procedure to automatically extract the road network from SPOT-HRV panchromatic images is proposed in a topographic map revision perspective. This procedure allows highly accurate results to be obtained independently of the density and the shape of the road network. The procedure is described in detail, along with our conclusions concerning the optimal conditions of its application. Some preliminary results are also shown concerning the introduction of a back-propagation neural network to extract the road network. This approach is considered to eliminate the problems associated with the grey level value and edge intervals. In the proposed procedure these intervals are necessary to detect the roads and must be specified every time to adapt to the particular radiometric content of a new image.     

Urban road extraction from high-resolution optical satellite images

In recent years, many approaches have been exploited for automatic urban road extraction. Most of these approaches are based on edge and line detecting algorithms. In this paper, a new integrated system for automatic extraction of main roads in high-resolution optical satellite images is present. Firstly, a multi-scale greylevel morphological cleaning algorithm is proposed to reduce the grey deviation of the road regions. Secondly, based on the greylevel difference between road surfaces and environmental objects, a colour high-resolution satellite image is segmented into a simplified imagemap by using the mean shift algorithm, which consists of three stages. The first stage deals with image filtering, the second stage deals with colour segmentation, and the third stage is proposed to fuse small regions in the segmented image. The mean shift filter algorithm not only smoothes the image, but also preserves abrupt changes (i.e. edges) in the local structure. The mean shift segmentation algorithm is a straightforward extension of the smoothing algorithm, which preserves discontinuity. From the histogram of the simplified imagemap, we can find the potential road surfaces, and use greylevel threshold to convert the segmented image into a binary one. The binary image is processed by using binary mathematical morphological closing and opening to remove small objects and to open the connected street blocks. We use a contour tracing algorithm to remove holes in street-block regions and to detect the street blocks' contours. In this research we found that many street blocks' contours were preserved perfectly, except for some of them which were depressed. Finally, we utilize the convex hull algorithm to smooth the street blocks' zigzag edges and to close the gaps in some street blocks, and then, we get the road edges. The integrated system for road network extraction is tested on the red band of an IKONOS multispectral image; all algorithms in this study are developed in C++ under Windows XP operating system. Results of the road network extraction are presented to illustrate the validation of the extracting strategy and the corresponding algorithms in this research, and future prospects are exposed.     

一个从多波段遥感图像提取道路网的算法

提出一个从多波段遥感图像中提取道路网的算法.首先,从多波段图像中提取直线段和平行线段,再进行融合处理,以克服图像中道路表示的不精确性.然后根据线段的局部特性,识别与道路约束模型符合程度好的路段.最后根据道路网的全局连接约束,识别与道路约束模型符合程度较弱的路段.该方法应用于三波段的卫星遥感图像,处理结果表明该方法是有效的.     

从高分辨率遥感影像中提取城市道路的新方法

在综合几种现有算法优点的基础上,提出一种新的道路提取策略。首先以角度纹理特性法分割原始影像;接着利用直线匹配原理剔除初始分割结果中的非道路地物,得到更为规则的道路条带;然后通过形态学手段获得道路中心线,并将每条中心线拆分为多段直线;结合上下文知识的马尔可夫模型被用于组织道路段的中心线,从而恢复完整道路网。实验结果表明：新方法具有良好的性能,可以从高分辨IKONOS遥感影像中提取出复杂的城市道路。     

Dempster-Shafer证据融合形状特征的高分辨率遥感图像道路信息提取

道路提取是遥感图像目标识别和提取中一项具有重要意义而困难的任务。在遥感图像道路提取的过程中,由于道路的不同形状和图像信息的复杂性,目前在许多基于形状特征提取道路的方法中,选取形状特征阈值时具有一定的难度,且需要大量的人工干预操作,缺乏一定的通用性,因此,本文提出一种基于DS(dempster-shafer)证据理论和形状特征的道路提取方法。该方法首先对道路的几何形状特征进行分析和优化,据此设计概率分配函数,并利用DS证据理论融合形状特征以获取道路段,最后通过道路连接操作得到道路的中心线。文末通过对典型道路图像和非典型道路图像的实验表明,该方法能够降低选取形状特征阈值的难度和对人工的依赖性,能适用于高分辨率遥感图像中直线型和曲线型道路的提取,具有一定的可行性。