QUANTITATIVE STUDY OF FAULT ACTIVITY BASED ON HIGH-PRECISION AIRBORNE LiDAR DATA: A CASE OF XIAOHONGSHAN FAULT IN XIANGSHAN-TIANJINGSHAN FAULT ZONE

High-precision and high-resolution topography are the basis of quantitative study of active tectonics. Traditional methods are mainly interpreted from the remote sensing image and can only obtain two-dimensional, medium-resolution DEM(5~10m grid unit)or local three-dimensional surface deformation characteristics. A combination of offset and micro-relief information is essential for understanding the long-term rupture pattern of faults, such as in seismic hazard evaluation. The recently developed high-resolution light detection and ranging(LiDAR)technology can directly carry out high-precision and omni-directional three-dimensional measurement of the landform, and provide fine geomorphologic data for the study of active tectonics, which is helpful to deepen the understanding of surface rupture process and fault activity characteristics. In this study, we take part of the Xiaohongshan Fault, the western segment of Xiangshan-Tianjingshan Fault located in Gansu Province(NE Tibet), as an example of how LiDAR data may be used to improve the study of active faults. Using the airborne LiDAR technology, we obtain the three-dimensional surface deformation characteristics with high accuracy and establish the three-dimensional topographic model of the fault geomorphic. A high-resolution digital elevation model(DEM)of the Jingtai-Xiaohongshan Fault was extracted based on high-precision LiDAR data. Then the faulted geomorphic markers(gullies, ridges and terraces)were measured in detail along the fault, and different offset clusters and long-term sliding vector of different segments of the fault were finally acquired. We obtained the 82 horizontal displacements and 62 vertical displacements of geomorphic markers. According to the offset amounts, we observed peaks in the histogram by using the method of cumulative offset probability density and interpreted that each peak may represent an earthquake that ruptured the Xiaohongshan Fault. The results show that the horizontal and vertical displacements fall into five clusters, and the smallest cluster may indicate the coseismic slip of the most recent earthquake, while the other clusters may represent the slip accumulation of multiple preceding earthquakes. The sliding vectors constrained by the horizontal and vertical displacement of several typical geomorphic markers show obvious differences on different segments of the fault. The results show that the fault segment is divided into three segments from west to east, which indicates that the fault activity is not uniform along the fault.     

影像地图集矢量要素与影像的协调处理

影像地图作为一种信息载体,其整体形象的信息价值和形式要求是不容忽视的。影像图集的统一协调性体现在很多方面,保证影像地图集的统一协调是编制高质量影像图集的基本保证,影像和矢量要素的协调处理是其中的一个重要内容。本文结合生产实践项目《广州市影像地图集》的设计制作,对图集编制过程中影像与矢量要素的统一协调处理提出了实用的设计方案。     

曲线矢量数据压缩算法实现及评析

制图综合是GIS的一个重要组成部分,它与GIS息息相关,当前已经成为GIS发展的一个瓶颈。曲线矢量自动综合是制图综合的一个重要方面。本文对当前制图综合中常用的曲线矢量数据压缩算法的可视化实现分别进行了评析。     

GPS基线相关性对平差结果的影响

根据GPS网平差的基本模型,从理论上分析了GPS基线相关性对GPS网平差结果的影响,推导了相关公式;并通过实例说明在精密GPS控制网平差时,应当考虑基线之间的相关性,以使解算结果达到毫米级精度。     

三分量数字检波器在ZY油田应用效果分析

在水平分量的炮集记录中,数字三分量检波器直达波的椭圆率明显呈现出线性偏振的形态,并具有较高的分辨率,而模拟三分量检波器直达波的线性偏振不清晰,抗干扰能力差.在频谱分析和能量曲线分析的对比中,数字检波器的性能也高于模拟检波器.在PP波弱波阻抗界面的沙河组沙三12段,PS波表现出强反射界面,而且构造幅度比PP波剖面明显.在PS波剖面上,剖面深处两边的构造联系清晰可见,而在PP波剖面上很难解释剖面两边构造之间的关系,表明PS波资料对深层界面的成像能力有时不比PP波能力差,多分量资料在构造勘探上具有互补性.在沙四层底钻遇气层的马62井和马11井的测线CDP位置上,PP波和PS波的振幅比剖面上表现出低振幅比异常区,与钻井结果吻合.用多分量衰减系数或衰减比剖面,能够识别砂岩含气/水产生所产生的高频衰减异常.多分量地震属性及其比值剖面是储层含气异常指示的有效参数.     

支持向量分类机LIBSVM方法识别天然地震、爆破与塌陷

对天然地震、爆破及塌陷的波形数据进行小波变换,并用小波转换系数提取香农熵特征,采用支持向量分类机LIBSVM多类模式识别方法对香农熵特征进行分类识别,识别率在80%~95%之间。结果表明,采用LIBSVM对波形特征进行分类的方法可以较好地识别天然地震、爆破与塌陷。     

Influence Analysis on the Floating Underwater Monitoring System Applicable for Very-Low-Frequency Acoustic Measurement

Ocean vector acoustic measurement is feasible affected by the hydrodynamic interference caused by the flow fluctuations and structural vibrations, especially in the very-low-frequency monitoring. Hence, a novel horizontal floating platform including a horizontal floating cable, vertical mooring cable and floating main body is proposed and described in this paper. It has the advantages of good maneuverability along with the current and multi-stage vibration isolation. The main application of this platform is to measure the ocean ambient noise coming from the wave fluctuation and the deterministic acoustic signals such as aquatic organisms, underwater targets and sailing vehicles. The influence of the current fluctuation on the attitude angle and flow induced vibration of cables and main body are analyzed with some previous sea test data. Moreover, the comparison between the vertical type platform used before and the horizontal type platform is also discussed. It is concluded that there is obvious relevance between the attitude angle and ocean current variation. Meanwhile, the abnormal influence on the main body is caused by the vibration transmission from the fluctuation of cables. There will be the influence on the accuracy of the acoustic measurement above 100 Hz, and the inherent vibration characteristic of the main body is the primary reason.     

空-谱角匹配与多指数法相结合的OLI遥感影像水体提取

针对复杂环境条件下水体遥感提取结果不连续且易与植被、建筑物、阴影相混淆的难题,基于Landsat 8 OLI影像,以石家庄市平山县岗南水库和宿迁市骆马湖附近河流为研究区,提出了一种空-谱角匹配与多指数法相结合的水体信息提取方法;并与单波段阈值法、归一化差分水体指数法（NDWI）、光谱角匹配法（SAM）、自动水体提取指数法（AWEI）和一类支持向量机法（OC-SVM）的水体提取结果进行对比分析和精度评定。试验结果表明,本文提出的方法兼顾了多特征之间的互补性优势,引入的空间信息有效地抑制了噪声的干扰,且以像素为基元的提取策略较好地保持了水体的边缘信息,避免了出现平滑掉细节信息的情况;与传统方法相比,本文方法受植被、建筑和阴影的干扰最小,对细小水体也具备较好的识别能力。     

WebGL在线动态地图服务框架设计

针对在线动态地图的交互性强、制图过程灵活、数据复杂多样、受众面广等特点及优势,本文基于WebGL技术设计了一种在线动态地图服务架构。该架构通过设计面向海量矢量数据的在线地图数据模型,定义在线地图切片的存储结构,并充分利用计算机硬件加速能力,实现了海量矢量切片数据的快速可视化和动态更新。为检验方法的可行性,利用该框架研发了某县的"多规合一"地理信息服务平台,结果表明,该框架提升了在线动态地图平台的实用性和操作性,为在线动态地图服务提供了可靠的理论和技术支撑。     

面向高光谱影像分类的显著性特征提取方法

针对高光谱影像分类问题,提出了一种显著性特征提取方法。首先,利用超像素分割算法将高光谱影像3个相邻波段分割为若干个小区域。然后,基于分割得到的小区域计算反映不同区域的显著性特征。最后,沿着光谱方向采用大小为3、步长为1的滑窗法获得所有波段的显著性特征。进一步将提取的显著性特征与光谱特征进行结合,并将结合后的特征输入到支持向量机中进行分类。利用Pavia大学、Indian Pines和Salinas 3组高光谱影像数据进行分类试验。试验结果表明,与传统的空间特征提取方法和基于卷积神经网络的高光谱影像分类方法相比,提取的显著性特征能够获得更高的高光谱影像分类精度,且结合光谱特征能够进一步提高分类精度。