基于分组排序的水汽层析约束ART算法     

丁楠  张书毕 《大地测量与地球动力学》2017,37(5):482-486

通过研究影响代数重构方法的因素,如松弛因子、投影次序、停止规则、非负约束,针对水汽层析方程组的特点,提出一种基于分组排序的水汽层析约束ART算法（WVTART）,并给出投影排序的去相关原则。实验分析证明,WVTART算法提高了收敛速度以及层析结果的精度。  相似文献   

新疆及周边地区强震成组活动及其预测研究   总被引：4，自引：0，他引：4  

高国英  王筱荣  温和平  聂晓红 《地震》2007,27(4):18-26

系统分析了1900年以来新疆及周边6级以上地震成组活动基本特征。 结果表明, 新疆及周边地区6级以上地震成组活动明显, 并具有持续时间短、 地震强度大、 频度高的特点。 新疆及周边地区7级以上地震有95％发生在地震成组活动期间, 地震成组活动是该区域发生7级以上强震的中期预测指标之一。 地震成组活动一般出现在低活动水平背景下, 而且成组地震活动在空间上相对集中分布, 在地震活动期间强震存在由新疆西南向北东迁移的特点, 其中天山地震带尤其是南天山西段为强震主要的活动区域。 地震成组活动伴随地震条带图像的出现; 在地震成组活动前或活动中新疆地区前兆测项异常明显增加, 具有群体异常的起伏变化过程。  相似文献   

Semiautomatic building extraction from stereo image pair based on lines grouping and least squares matching     

Zhang Zuxun  Hu Xiangyun  Zhang Jianqing 《地球空间信息科学学报》2013,16(4):49-55

The paper presents a general paradigm of semiautomatic building extraction from aerial stereo image pair. In the semiautomatic extraction system, the building model is defined by selected roof type through human-machine interface and input the approximation of area where the extracted building exists. Then under the knowledge of the roof type, low-level and mid-level processing including edge detection, straight line segments extraction and line segments grouping are used to establish the initial geometrical model of the roof-top. However, the initial geometrical model is not so accurate in geometry. To attain accurate results, a general least squares adjustment integrating the linear templates matching model with geometrical constraints in object-space is applied to refine the initial geometrical model. The adjustment model integrating the straight edge pattern and 3D constraints together is a well-studied optimal and anti-noise method. After gaining proper initial values, this adjustment model can flexibly process extraction of kinds of roof types by changing or assembling the geometrical constraints in object-space.  相似文献   

低分辨率遥感影像中道路的全自动提取方法研究   总被引：1，自引：0，他引：1  

洪日昌  吴秀清  刘媛  尹东 《遥感学报》2008,12(1):36-45

从Marr视觉计算理论出发,利用低分辨率遥感影像的特点,提出了一种基于边缘线段感知编组和动态规划跟踪线段的道路信息全自动提取方法.首先分析了低分辨率影像中道路的辐射特性和几何特性,以得到道路模型.然后在底层处理阶段对影像进行边缘检测、无效线段去除等预处理;中层处理阶段采用基于上下文关联的感知线段编组法得到候选道路段,并由道路段的置信度阈值确定道路种子点;最后在高层处理阶段提出基于动态规划的道路跟踪算法得到候选道路,并且采用知识推理去除部分虚警.实验结果表明:(1)对图像中背景干扰较大的山区道路和复杂的城区道路网均有较好的识别效果;(2)识别过程全自动进行,没有人工干预,因此计算效率相比其他方法有一定的优势;(3)由不同传感器卫星获取的影像如L7,SPOT,SAR等,算法均能进行有效识别,具有很好的普适性和稳健性.  相似文献   

Recognizing building groups for generalization: a comparative study   总被引：1，自引：0，他引：1  

Min Deng  Jianbo Tang  Fang Wu 《制图学和地理信息科学》2018,45(3):187-204

Recognition of building groups is a critical step in building generalization. To find building groups, various approaches have been developed based on the principles of grouping (or the Gestalt laws of grouping), and the effectiveness of these approaches needs to be evaluated. This study presents a comparative analysis of nine typical such approaches, including three approaches that only consider proximity principle and six approaches that consider multiple grouping principles. Real-life dataset at 1:5000, 1:10,000, and 1:50,000 scales provided by National Geomatics Center of China is used to evaluate the performance of these approaches. Buildings at smaller scales are used to construct the benchmarks to test the grouping results at larger scales, and the adjusted Rand index is adopted to indicate the accuracy of the detected groups. Significant tests (Friedman test and Wilcoxon signed-rank test) are also performed to provide both the overall and pairwise comparisons of these approaches. The results show that (1) the average accuracy of most existing approaches is between 0.3 and 0.5, and the performances of these approaches are significantly different; (2) when only proximity is considered, the buffer analysis approach performs significantly better than other approaches; (3) when multiple grouping principles are considered, the local constraint-based approach usually performs better than other approaches; (4) existing approaches that consider similarity and/or continuity seldom improve the performance of building grouping.  相似文献   

Stereo analysis of high-resolution SAR images for building height estimation in cases of orthogonal aspect directions     

Uwe Soergel  Eckart Michaelsen  Antje Thiele  Erich Cadario  Ulrich Thoennessen 《ISPRS Journal of Photogrammetry and Remote Sensing》2009,64(5):490-500

SAR stereo image analysis for 3D information extraction is mostly carried out based on imagery taken under same-side or opposite-side viewing conditions. For urban scenes in practice stereo is up to now usually restricted to the first configuration, because increasing image dissimilarity connected with rising illumination direction differences leads to a lack of suitable features for matching, especially in the case of low or medium resolution data. However, due to two developments SAR stereo from arbitrary viewing conditions becomes an interesting option for urban information extraction. The first one is the availability of airborne sensor systems, which are capable of more flexible data acquisition in comparison to satellite sensors. This flexibility enables multi-aspect analysis of objects in built-up areas for various kinds of purpose, such as building recognition, road network extraction, or traffic monitoring. The second development is the significant improvement of the geometric resolution providing a high level of detail especially of roof features, which can be observed from a wide span of viewpoints. In this paper, high-resolution SAR images of an urban scene are analyzed in order to infer buildings and their height from the different layover effects in views taken from orthogonal aspect angles. High level object matching is proposed that relies on symbolic data, representing suitable features of urban objects. Here, a knowledge-based approach is applied, which is realized by a production system that codes a set of suitable principles of perceptual grouping in its production rules. The images are analyzed separately for the presence of certain object groups and their characteristics frequently appearing on buildings, such as salient rows of point targets, rectangular structures or symmetries. The stereo analysis is then accomplished by means of productions that combine and match these 2D image objects and infer their height by 3D clustering. The approach is tested using real SAR data of an urban scene.  相似文献   

基于几何约束与局部描述的航空影像直线匹配     

卓广平  张俊花 《测绘通报》2022,(3):60-64

针对航空影像场景复杂,干扰直线匹配的不确定因素较多的问题,本文提出了基于几何编组与局部均值标准差直线描述符(MSLD)的直线匹配算法。首先,利用直线检测器(LSD)获得影像的直线特征信息,将直线与直线间的几何特征作为约束条件进行编组,获得两幅航空影像的直线对;其次,运用核线约束确定候选直线对,并依次构建参考与候选直线对的支持区域,利用仿射不变性统一支持区域的大小,借助MSLD进行直线对外观的局部描述;然后,结合欧氏距离与最邻近比值计算航空影像中直线描述符间的相似性,进而确定匹配结果;最后,结合共线约束完成对匹配结果的检核,获取精确的同名直线。试验选择不同场景类型变换下的航空影像数据,结果证明了本文算法可以较好地应对航空影像直线匹配效果不佳的现象。  相似文献   

一种基于感知分组和结构特征的道路交叉口识别方法     

蒙艳姿  徐柱  刘国祥  蔡国林 《测绘科学》2010,35(4):106-108,99

为了能从矢量地图中准确、快速地识别道路交叉口,本文将感知分组方法与道路交叉口的典型结构特征结合,提出了一种基于感知分组和结构特征的道路交叉口识别方法。为检验算法的有效性,选取两块典型区域即简单道路网和复杂道路网进行实验分析。结果表明,该算法能快速、准确地识别道路交叉口,且具有良好的稳定性和灵敏性。  相似文献   

Performance‐based grouping methods of bridge classes for regional seismic risk assessment: Application of ANOVA,ANCOVA, and non‐parametric approaches          下载免费PDF全文

Sujith Mangalathu  Jong‐Su Jeon  Jamie E. Padgett  Reginald DesRoches 《地震工程与结构动力学》2017,46(14):2587-2602

One of the key tasks to enable a regional risk assessment is to group structures with similar seismic performances and generate fragility curves representative of the grouped structures. The grouping has been traditionally performed based primarily on engineering judgment and prior experience. This paper (i) presents an overview of various statistical techniques such as analysis of variance, analysis of covariance, and Kruskal–Wallis test for grouping the bridges of similar performance; (ii) compares the groupings that emerge from the various grouping techniques; and (iii) identifies the method that has more statistical power in creating bridge sub‐classes of distinct structural performance. The grouping is achieved by comparing the structural responses of bridge classes obtained from the non‐linear time history analysis of bridges. The relative merits of these grouping techniques are discussed with the case study of box‐girder bridges in California. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

联合Bi-LSTM和注意力加强多尺度卷积的黄河三角洲湿地高光谱图像分类方法研究          下载免费PDF全文

徐美论  李忠伟  王雷全  李娟  胡亚斌  梁建 《海洋科学》2023,47(5):27-40

近年来,面向黄河口的监测需求日益增大,如黄河入海流路改道至清水沟路以来,在新老河道的交汇处存在着丰富的地物类别,对于这些地物类别的检测识别研究有助于掌握生态环境状态,对于黄河口的湿地保护以及国家改善环境的战略支持具有重要意义。因此,本文提出一种新的湿地高光谱图像分类方法,分双路分别提取图像的空谱特征并融合分类。光谱维采用分组预处理的双向长短期记忆网络(Bi-LSTM)有效学习光谱特征;空间维采用注意力加强的多尺度卷积网络有效增强所提取的空谱特征,使得分类结果更具准确性。本文实验应用覆盖黄河入海口新老河道交界处的成像光谱仪(Compact High Resolution Imaging Spectrometer,CHRIS)所采集的数据和黄河三角洲自然保护区滨海湿地高分5号传感器(GF-5)所采集的高光谱图像开展。结果表明:分组与双向长短期记忆网络(Bi-LSTM)的有效结合显著提升了网络性能,同其他监督分类方法相比提升约3%~8%,此外注意力机制的加入同比增加约3%,在使用1%的极少训练集下数据集CHRIS和GF-5的总体分类精度分别达到92.3%和86.11%。  相似文献