高分六号遥感卫星新增波段下的树种分类精度分析     

张沁雨  李哲  夏朝宗  陈健  彭道黎 《地球信息科学学报》2019,21(10):1619-1628

高分六号卫星具有覆盖广、多种分辨率、波段多的优势,能为遥感解译提供更丰富的信息。为探究高分六号卫星新增波段在森林树种识别上的应用,本文以覆盖根河市阿龙山林业局的一期高分六号宽幅影像为数据源,基于特征优化空间算法（Feature Space Optimization,FSO）和最大似然分类法,分别利用高分六号的前4个波段和所有波段（8波段）的光谱、纹理等特征进行了森林树种分类,并逐一添加新增波段特征确定了各波段的贡献率排名。结果表明：在加入了优选出的均匀性纹理、均值纹理和角二阶矩纹理3种纹理特征后,前4波段和8波段的分类精度比只基于光谱特征时的精度分别高出13.23%和24.63%;利用8波段信息比只利用前4波段在基于光谱特征上的精度高11.88%,在基于光谱+纹理特征上则高23.24%;基于8波段光谱+纹理特征的树种分类精度最高,达到68.74%,新增4波段的贡献率排名为B6>B5>B8>B7,说明新增红边波段对于本次树种分类试验的贡献率最高,能为北方树种识别提供有效帮助。  相似文献   

GPS/PWV时间序列特征提取方法的研究     

胡广保  叶世榕  张彦祥  夏朋飞  夏凤雨 《大地测量与地球动力学》2019,39(1):36-40

针对GAMIT/GLOBK软件解算得到的4 a GPS/PWV时间序列的特征提取问题，提出基于滤波辅助的部分集成经验模态分解（PEEMD）与Hilbert谱分析相结合的特征提取方法。首先，在PEEMD方法的基础上,结合滤波辅助的PEEMD方法与Hilbert谱分析，建立GPS/PWV时间序列特征提取模型；然后，将所提出的方法应用于TNML测站4 a的GPS/PWV长时间序列和7 d的GPS/PWV短时间序列分析中，并将滤波辅助的PEEMD结果与传统的小波分解结果进行对比。结果表明，该特征提取方法能准确有效地提取出 GPS/PWV时间序列中的周年周期和日周期特征分量，滤波辅助的PEEMD分解结果与小波分解结果一致，且提取的特征分量与原始信号更加吻合。  相似文献   

阿拉善左旗5.8级地震前地脉动信号特征分析          下载免费PDF全文

梁沙沙  高立新  薛丁  戴勇  格根 《地震工程学报》2018,40(4):808-814

本文针对2015年4月15日发生在南北地震带北端的阿拉善左旗5.8级地震,利用乌海台、东升庙台、石嘴山台的连续数字地震波形资料,采用快速傅里叶变换对三个台站的2015年4月1日00时—4月15日23时波形数据进行分析,并持续跟踪0~0.25 Hz包络幅值极大值的变化形态。结果显示:(1)在5.8级地震前,震中附近的乌海地震台、东升庙地震台、石嘴山地震台记录的地震波形均出现频谱向低频偏移的现象;(2)三个台站出现低频异常的包络幅值极大值跟踪形态不一致,其中只有乌海台在震前出现明显的持续不稳定异常,异常持续时间约120h;(3)三个台站距离震中由近及远包络幅值极大值的跟踪形态差异明显。  相似文献   

结合图像增强和恢复的增强现实跟踪注册     

郭士祥  范铀  范冲 《测绘通报》2020,(8):39

增强现实中的跟踪注册技术一直是研究的重点和难点，而地下矿道和巷道内亮度低，产生的图像较昏暗，车载相机快速运动和抖动，对传统的基于特征匹配的跟踪注册提出了挑战。本文从提高增强现实中跟踪注册稳健性和精度出发，采用基于Retinex改进的方法增强昏暗图像的亮度，同时利用基于对抗神经网络的方法恢复运动模糊图像。首先提取图像ORB特征，实现初始化；然后根据跟踪特征点的数量，开启图像增强和图像恢复线程，提高特征点提取质量和数量。在数据集和真实模拟场景下的试验结果显示，跟踪精度提高了12%左右，在低亮度和含有轻微模糊的情况下，跟踪注册稳健性也有显著提高。  相似文献   

结合PS特征点的SBAS地表形变监测     

聂运菊  熊佳诚  程朋根  罗跃 《测绘通报》2020,(4):91-95

针对SARscape SBAS技术存在人工选取地面控制点影响监测结果的问题，本文提出了一种结合PS特征点的SBAS地表形变监测方法。通过设置PS技术中的振幅离差指数与相干性阈值，提取PS监测结果中的特征点作为地面控制点进行轨道精炼与形变反演。以2017年3月至2018年12月覆盖南昌地区的Sentinel-1影像为数据源，进行了地表形变监测与验证。结果表明：①该方法与PS方法监测结果均显示南昌市城区在监测时段内整体呈小幅度上升趋势，年平均沉降速率相关性达到了0.959，具有高度一致性。②将该方法、PS方法、人工选取地面控制点的SBAS方法的监测结果与水准数据进行对比，该方法与水准数据的误差不超过3.5 mm，说明了该方法的有效性。  相似文献   

THE RESPONSE OF FLUVIAL GEOMORPHOLOGIC CHARACTERISTICS OF THE FUJIANG DRAINGE BASIN TO ACTIVITY OF THE HUYA FAULT ZONE     

LIANG Ou-bo  REN Jun-jie  L&#  Yan-wu 《地震地质》2018,40(1):42-56

The Huya Fault, located in the steep topographic boundary of the Minshan Mountains in the eastern margin of the Tibetan plateau, has documented many major earthquakes such as the 1630(M=6 3/4), 1973 Huanglong(M_S=6.5) and the 1976 Songpan-Pingwu earthquake swarm(M_S=7.2, 6.7, 7.2). While its activity remains unclear because of lacking Quaternary sediments. In the past few decades, there have been significant advances in understanding the relationship between bedrock channel landscapes and active tectonics, indicating that the bedrock fluvial features can well record the tectonic activity. Many studies reveal that tectonism is the primary factor of landscape evolution in tectonically active regions, and the erosional landscapes can be used to reveal tectonic signals on timescales of 10³~10⁶ years. The Huya Fault crosses the Fujiang drainage basin, making it suitable for the study of bedrock rivers and tectonic uplift in the eastern margin of Minshan. In this study, we calculate the geomorphologic indeices(hillslope, local relief, normalized steepness indices and hypsometric integral) on the basis of the digital elevation model(DEM) SRTM-1. For better understanding the tectonic activity along this fault, we derive some small catchments on the two sides of the Huya fault to analyze the differences of average steepness indices and hypsometric integral. Combining with field observations, lithology, precipitation and modern erosion rates, this study suggests that tectonic activity is the controlling factor of geomorphology in the eastern margin of the Minshan Mountains. We use focal mechanism solutions, GPS data and geomorphic evidence to explore the relationship between the geomorphologic indices of the Fujiang drainage and activity characteristics of the Huya fault. Our results suggest that:(1) The Fujiang drainage basin is in a steady state. The characteristics of the knickpoints indicate that they are mainly controlled by the locally resistant substrate. (2) The suggested value of the geomorphologic index on the west side of the Huya fault is generally larger than on the east side, showing differential tectonic uplift rates across the fault. (3) The difference of the geomorphologic index of the small catchments on both sides of the Huya fault is gradually increasing from north to south along this fault, in accordance with that the north and south segments of the Huya fault are dominated by strike-and reverse-slip, respectively.  相似文献   

九寨沟M_S7.0地震的前兆异常时空演化特征及其分析     

张小涛  宋治平  李纲 《中国地震》2018,34(4):772-780

以2017年8月8日九寨沟MS7.0地震震中为中心,对震前不同震中距前兆异常的时空演化过程进行分析。研究表明,震中距100km范围内无前兆异常,前兆异常主要分布在震中距100～500km范围内。震前2年新增前兆异常开始逐渐增多;不同震中距范围内的新增异常测项所占比例在震前1.5年左右达到最大,在震前又降低。在震中距300km范围内的异常测项所占比例相对较高。前兆异常时空演化过程存在3个不同的变化阶段,即α阶段(前兆异常的早期阶段,包括α_1和α_2,震前1000天以上)的异常主要分布在震中东北方向和西南方向,异常具有向外扩展的特征;β阶段(前兆异常的中期阶段,震前500～1000天)的异常表现为大范围出现异常;γ阶段(前兆异常的短期阶段,包括γ_1和γ_2,震前500天内)的异常分布在震中的东北方向,表现为远源区的异常向震中收缩过程(γ_1)和近源区的异常向外扩展的过程(γ_2)。通过与其他震例对比分析发现,前兆异常的3个阶段现象可能是大震前的共性特征,大震前前兆异常的显著增加对发震时间的预测具有一定的指示意义。  相似文献   

甘肃省地热资源赋存特征及潜力评价     

谢娜  喻生波  丁宏伟  张明泉 《中国地质》2020,47(6):1804-1812

甘肃省地热资源丰富，其地热资源的开发利用具有较大的潜力。本文介绍了甘肃省地热资源分布概况，结合地区构造、地热水化学特征、地热资源量及开发利用现状探讨了甘肃隆起山地对流型与沉积盆地传导型地热资源的赋存特征，并对两种类型地热资源潜力进行了分析评价。结果表明，沉积盆地地热资源分布于河西、陇西及陇东盆地等，热储类型为裂隙型和孔隙型，热储层自元古宙至新生代均有发育，岩性以砂岩为主；隆起山地型地热资源主要分布于祁连山和西秦岭造山带，热储类型为断裂破碎带，岩性以花岗岩为主；通过潜力计算得知，全省热量开采系数≥0.4的仅占29.17%，表明目前甘肃地热资源开采程度较低，开采潜力较大。  相似文献   

基于计算机视觉的头足类角质颚特征研究Ⅰ:轮廓与特征点提取     

贺芊菡  孙翁杰  刘必林  孔祥洪  林龙山 《海洋与湖沼》2020,51(6):1493-1500

轮廓与特征点研究是头足类角质颚形态特征鉴别的基本方法，对于轮廓与特征点的提取最常用的方法是手动描绘与标定，利用计算机视觉进行轮廓与特征点的提取，不仅可以降低手动提取带来的误差、提高准确性，而且更加快速、便捷。文章将利用计算机视觉提取头足类角质颚的轮廓与特征点，首先将自制装置拍摄得到的角质颚三视图放入MTALAB软件中进行编程处理，然后利用Canny算法提取角质颚轮廓，最后根据地标点的定义标定特征点位置并建立空间坐标系得到角质颚的特征点坐标。研究结果显示，利用计算机视觉提取角质颚的轮廓图像以及特征点坐标是可行的，当标准差σ取值为0.1时角质颚轮廓图效果最佳，在得到的轮廓图上进行特征点的标定，通过迭代遍历轮廓图获得各个特征点的空间坐标。研究分析认为，将计算机视觉应用于头足类角质颚形态学的研究可以提高研究的便捷性，同时也为后续的研究提供了新的实验思路和方法。  相似文献   

SLIP OFFSET ALONG STRIKE-SLIP FAULT DETERMINED FROM STREAM TERRACES FORMATION          下载免费PDF全文

XU Bin-bin  ZHANG Dong-li  ZHANG Pei-zhen  ZHENG Wen-jun  BI Hai-yun  TIAN Qing-ying  ZHANG Yi-peng  XIONG Jian-guo  LI Zhi-gang 《地震地质》2019,41(3):587-602

Slip rate is one of the most important parameters in quantitative research of active faults. It is an average rate of fault dislocation during a particular period, which can reflect the strain energy accumulation rate of a fault. Thus it is often directly used in the evaluation of seismic hazard. Tectonic activities significantly influence regional geomorphic characteristics. Therefore, river evolution characteristics can be used to study tectonic activities characteristics, which is a relatively reliable method to determine slip rate of fault. Based on the study of the river geomorphology evolution process model and considering the influence of topographic and geomorphic factors, this paper established the river terrace dislocation model and put forward that the accurate measurement of the displacement caused by the fault should focus on the erosion of the terrace caused by river migration under the influence of topography. Through the analysis of the different cases in detail, it was found that the evolution of rivers is often affected by the topography, and rivers tend to migrate to the lower side of the terrain and erode the terraces on this side. However, terraces on the higher side of the terrain can usually be preserved, and the displacement caused by faulting can be accumulated relatively completely. Though it is reliable to calculate the slip rate of faults through the terrace dislocation on this side, a detailed analysis should be carried out in the field in order to select the appropriate terraces to measure the displacement under the comprehensive effects of topography, landform and other factors, if the terraces on both sides of the river are preserved. In order to obtain the results more objectively, we used Monte Carlo method to estimate the fault displacement and displacement error range. We used the linear equation to fit the position of terrace scarps and faults, and then calculate the terrace displacement. After 100, 000 times of simulation, the fault displacement and its error range could be obtained with 95%confidence interval. We selected the Gaoyan River in the eastern Altyn Tagh Fault as the research object, and used the unmanned air vehicle aerial photography technology to obtain the high-resolution DEM of this area. Based on the terrace evolution model proposed in this paper, we analyzed the terrace evolution with the detailed interpretation of the topography and landform of the DEM, and inferred that the right bank of the river was higher than the left bank, which led to the continuous erosion of the river to the left bank, while the terraces on the right bank were preserved. In addition, four stages of fault displacements and their error ranges were obtained by Monte Carlo method. By integrating the dating results of previous researches in this area, we got the fault slip rate of(1.80±0.51)mm/a. After comparing this result with the slip rates of each section of Altyn Tagh Fault studied by predecessors, it was found that the slip rate obtained in this paper is in line with the variation trend of the slip rate summarized by predecessors, namely, the slip rate gradually decreases from west to east, from 10~12mm/a in the middle section to about 2mm/a at the end.  相似文献