An optimized use of limited ground based topographic data for river applications     

Mohamed Jaballah  Benoit Camenen  André Paquier  Magali Jodeau 《国际泥沙研究》2019,34(3):216-225

A prime requirement for hydrological applications,such as sediment budgeting or numerical modelling,is that produced Digital Terrain Models(DTMs)accurately represent the shape of landforms,especially for river reaches where data are not homogeneous.DTM error is a function of data point measurement accuracy and density and also of the field survey strategy when limited amounts of data will be acquired.This paper aims to advance the importance of the field survey strategy for the specific,but common cases,where only limited topographic data will be available.This methodology is based on the idea that any feature can be properly described by a set of cross sections and breaklines describing both main and secondary directions of the flow.Then,a longitudinal linear interpolation can be applied to the defined homogeneous zones.This morphologically oriented(MO)method that includes data acquisition strategy and interpolation,was validated using a reference DTM derived from LiDAR measurements.An estimation of the uncertainties also is suggested based on the distance of the nearest point and the local slope using a geographically weighted regression.The proposed MO method is typically applicable to Alpine river reaches characterized by multiple channels that may always be underwater and not navigable such as an alternate bar system with secondary and transverse channels.  相似文献   

多连通域中的插值序列     

张庆德 《成都信息工程学院学报》1987,(2)

本文给出了多连通域(由有限个连续统所界)上点列为H~∞(D)插值序列的几个等价条件。这些条件是保形不变的。  相似文献   

GPS网络RTK系统的内插算法研究   总被引：1，自引：0，他引：1  

卫柳艳  岳东杰 《现代测绘》2008,31(5)

本文详细介绍了GPS网络RTK系统中内插算法的基本原理和计算公式，并进行了模拟计算，从而验证了内插算法的精度和可靠性。  相似文献   

A simple data transformation technique for pre-processing survey data at embayed beaches     

Mitchell D. Harley  Ian L. Turner 《Coastal Engineering》2008

This note explains a technique used for pre-processing three-dimensional survey data obtained at embayed beaches that exhibit distinct alongshore curvature. Using a log-spiral function fitted to the beach planform, the data is transformed from Cartesian into an alternative alongshore–cross-shore coordinate system. When undergoing this transformation, the curvature in the survey data is effectively removed. This greatly simplifies the application of standard interpolation methods, and in this transformed coordinate system the alongshore and cross-shore directions are now explicitly defined. Using a property unique to the log-spiral, the interpolated data is readily transformed back into the original Cartesian coordinate system for further analyses and interpretation. The practical application and advantages of this technique are then demonstrated using survey data from two embayed beaches in south-eastern Australia.  相似文献   

基于偏微分方程的定向插值在偏移成像中的应用     

韩复兴  孙章庆  陈祥忠  高正辉  王瑞兴  刘俊成  王丽丽 《地球物理学报》2021,64(3):1006-1015

对于射线类偏移成像来说,求解射线追踪系统中所涉及的属性值不在网格节点上的插值计算问题是一个非常重要的环节,它影响到求解走时、路径和振幅信息的计算效率和精度,进而影响到整个偏移成像的质量和效率.本研究根据速度模型的空间梯度特点,考虑被插值点处速度的梯度在横向和纵向的分布特征,构建基于速度梯度空间变化的偏微分方程算法,将近几年发展起来的基于偏微分方程的定向插值算法引入到射线类偏移成像当中,实现射线追踪当中涉及的属性值不在网格节点上的插值计算.由于偏微分方程法本身固有的特性(局部特征不变性、解的唯一性和线性叠加性),因此,该算法可以实现不破坏原始速度模型空间梯度结构的非网格节点属性的插值计算.通过在常用的速度模型上的插值计算对比、不同速度模型上射线路径对比分析以及复杂介质模型上最后的偏移成像结果分析可以得出,应用基于速度梯度构建的偏微分方程插值算法在进行插值计算的过程当中可以实现不破坏原始速度模型空间速度梯度结构的属性计算,同时应用该算法可以最终提高射线类偏移成像的质量.  相似文献   

局部动态最优Voronoi图的NNI算法及其在格网数字水深模型中的应用     

董箭  彭认灿  郑义东  王涛 《测绘学报》2013,42(2):284-303

在分析传统自然邻点插值(NNI)算法局限性的基础上,依据Voronoi单胞和Delaunay三角形的几何特性,提出基于局部动态最优Voronoi图的NNI算法。阐述该算法的基本原理和实现步骤,并在VC++环境下结合多波束测深数据对其在格网数字水深模型(Grid-DDM)中的应用进行了验证。试验表明该算法具有执行效率高、插值精度不丢失等优点。  相似文献   

The development of a historical digital cadastral database†     

GARY J. HUNTER  IAN P. WILLIAMSON 《International journal of geographical information science》2013,27(2):169-179

With an ever-increasing number of land information systems being developed, there is a growing demand by users for systems which support the use of temporal data for time-based studies. System managers, however, may have difficulty responding to these calls because of the lack of available research to guide them in their task. This paper examines the simple method of storing and processing temporal graphical data by the addition of time-encoding attributes to data elements as required. To illustrate the technique, a historical digital cadastral database has been created which al lows users to display and report on the cadastral parcellation of a region at any time in the past. The method can also be widely applied to other data to assist a broad range of space/time-related studies.  相似文献   

海洋数据仓库的数据清洗规则应用研究          下载免费PDF全文

李郅明  余荣君  叶馥榕 《海洋开发与管理》2018,35(2):94-97

建立海洋数据仓库以实现海洋多源信息的汇集融合已成为趋势,数据清洗是数据仓库建立过程中的重要环节。文章介绍基于滤波和离差法的数据清洗规则,并以厦门市海洋水温数据为例,采用该规则方案对异常值进行批量探测和修正,得到较好效果,可为数据挖掘技术的研究和应用提供支持。  相似文献   

An algorithm for interpolation in the pyramid domain‡     

Antoine Guitton  Jon Claerbout 《Geophysical Prospecting》2010,58(6):965-976

With the pyramid transform, 2D dip spectra can be characterized by 1D prediction‐error filters (pefs) and 3D dip spectra by 2D pefs. These filters, contrary to pefs estimated in the frequency‐space domain (ω, x) , are frequency independent. Therefore, one pef can be used to interpolate all frequencies. Similarly, one pef can be computed from all frequencies, thus yielding robust estimation of the filter in the presence of noise. This transform takes data from the frequency‐space domain (ω, x) to data in a frequency‐velocity domain (ω, u=ω·x) using a simple mapping procedure that leaves locations in the pyramid domain empty. Missing data in (ω, x) ‐space create even more empty bins in (ω, u) ‐space. We propose a multi‐stage least‐squares approach where both unknown pefs and missing data are estimated. This approach is tested on synthetic and field data examples where aliasing and irregular spacing are present.  相似文献   

Robust reconstruction of aliased data using autoregressive spectral estimates     

Mostafa Naghizadeh  Mauricio D. Sacchi 《Geophysical Prospecting》2010,58(6):1049-1062

Autoregressive modeling is used to estimate the spectrum of aliased data. A region of spectral support is determined by identifying the location of peaks in the estimated spatial spectrum of the data. This information is used to pose a Fourier reconstruction problem that inverts for a few dominant wavenumbers that are required to model the data. Synthetic and real data examples are used to illustrate the method. In particular, we show that the proposed method can accurately reconstruct aliased data and data with gaps.  相似文献