Feasibility of Coupled Pattern Reconstruction Technique in the Detection of Internal Waves

A key problem of contemporary static and kinematic positioning is the problem of transformation of conformai coordinates of universal Mercator projection (UMP) type from a local datum (regional, national) to a global datum, for instance, the World Geodetic System 1984 (WGS 84) with reference to Boyle (1987). Such a problem is met if we use WGS 84 GPS‐derived ellipsoidal coordinates of a point for localization in a local chart of UMP type. In this article we derive and test the equations of a curvilinear datum transformation of ellipsoidal GPS coordinates in a global datum to conformai coordinates of UMP type in a local datum. The curvilinear datum transformation includes three parameters for translation, three parameters for rotation, one scale parameter, and two form parameters which account for a change in the semimajor axis and in the relative eccentricity of the reference ellipsoid.     

ECHOBASE—A portable geographic fishery research database system

A geographic fishery research database system (GFRDBS), called ECHOBASE, for storing and management of data on pelagic fish resources from acoustic surveys and catch samples, combined with environmental data in a geographic context, has been developed. The system constitutes a portable and inexpensive yet powerful tool for fishery research and environmental monitoring and provides on‐board data processing and mapping capabilities.

Data are acquired from an echosounder, echo signal processor, environmental profiler (CTD probe), and Global Positioning System (GPS) receiver. The electronic digitized maps (based on C‐MAP public format files) provide active on‐screen nautical charts.

The basic GFRDBS platform is a portable PC 486 machine, which is used as an on‐board data acquisition and processing tool running under MS Windows 3.1 operating environment. The system is designed around the Borland's PARADOX package, which provides a relational database for managing acoustic, catch, and environmental data. The ECHOBASE programs were written in Borland C ++ language as a Windows application.     

长江口海图深度基准面换算关系研究

长江口不同时期的海图采用的深度基准面不一样 ,为充分利用诸多历史海图资料 ,需要了解历史海图深度基准面之间的关系。本文介绍了海图理论深度基准面 (前苏联弗拉基米斯基的低潮面 )的推算方法 ,用Matlab语言实现了对海图理论深度基准面的人机交互式计算。利用 1977年实测潮位资料计算获得的调和常数 ,计算了长江口 10个验潮站的深度基准面 ,探讨了不同深度基准面之间的换算关系     

DGPS在广西沿海海底地形测绘中的应用

DGPS（DifferentialGlobalPositioningSystem）测量技术即差分定位技术,包括实时差分和后处理差分定位技术,正在远海和近海测量中得到广泛应用。后处理差分定位与微波定位及GPS实时差分定位相比,具有作用距离远,不受基准台与船台之问的障碍物影响以及减少基准台等优点。对于近海大比例尺（大于1：1万）测量,可采用实时差分定位的方法,而小于1：1万中小比例尺海底地形图测绘及海上其他工程测量,采用后处理差分定位,既能满足精度要求,又能提高工作效率。本文主要介绍利用DGPS后处理定位方法,在测绘广西沿海1：5万海底地形图中的应用情况。     

我国海域无缝垂直基准面的选择

介绍了椭球面、大地水准面、平均海面和海图深度基准面的定义。系统分析了潮汐基准面和大地水准面不适合作为无缝垂直基准面的原因,及以椭球面作为无缝垂直基准面的合理性和可行性,并建议选择WGS84椭球面作为我国海域的无缝垂直基准面。     

Combining historical and new hydrographic data

The NOAA National Ocean Service hydrographic surveys run between 1930 and 1965 have been digitized from the paper smooth sheets. The surveys since 1965 have been collected, processed, and stored in digital form. The new multibeam systems have been used since 1984 to cover over 100,000 square nautical miles of the Exclusive Economic Zone with overlapping swaths of digital soundings. Each of these multibeam surveys may contain millions of soundings. None of the above data has been assigned quality control tags by NOS, but they are stored by survey number, with indexes showing what younger data are available to supersede older data in any area.

Large digital databases, such as the Master Seaftoor Digital Database, are planned in connection with the Defense Hydrographic Initiative. It will be necessary to assign quality control ratings to the soundings in the databases. The detailed survey data may be indexed in the master database but maintained in distributed databases. The databases could supply historical sounding data in digital form for the planning, collection, processing, and evaluation of new survey data.

During the compilation of some bathymetric maps and nautical charts, it is necessary to junction and combine the newer multibeam surveys having total bottom coverage, with the more widely spaced historical data. Precedence is given to the newer hydrographic data, with some older data being removed as needed in order to provide a smooth transition between data sets. In applying multibeam data to nautical charts, it is necessary that actual soundings be positioned properly with respect to bottom contours, which may have been drawn using gridded values. The junctioning of historical and newer data sets is expected to be aided by the use of interactive cartographic workstations.     

RTK GPS在海岸工程中的应用

随着GPS技术的发展，具有RTK功能的GPS接收机不但在平面位置上可以达到厘束级，而且以WGS84为参考椭球的垂直高程也可以达到厘束级，因而被广泛地应用于海岸带测量中。本文介绍了RTKGPS在海域勘界、无验潮模式水深测量方面的一些具体应用。     

合理基准变换改进海图水深精度的方法研究

在海图深度基准面不一致的情况下,使用制图资料标绘新海图图载水深数字,或者由海图确定实际水深数值时,需要准确把握制图资料、新旧海图和潮汐起算面的深度基准关系。通过分析现有海图深度基准存在的问题,对不同海图深度基准面之间的关系及其数值的查实与确定进行了研究,并针对海图深度基准面实际应用和研究的状况,提出了合理基准变换改算水深数据的方法。实际应用表明,该方法可将图载水深改算到同一深度基准面,对于改进海图水深数据精度具有积极意义。     

海岸带遥感影像与海图融合显示技术研究

针对海岸带遥感影像和海图综合显示问题展开研究,以Osg Earth数字地球平台为基础,将遥感影像和电子海图分别以瓦片服务形式进行加载,通过GPU对数据瓦片进行着色处理,在终端进行数据叠加实现融合显示。实验结果表明,该方法能够实时提供浮雕、黑白、透明度叠加等显示效果,为海岸带遥感影像与海图综合可视化提供了一种可行的技术方案。     

编制北极地区航海图有关问题的探讨

介绍了北极的概念,从海图投影、制图资料、专题符号、海图分幅等4个方面,研究了当前编制北极地区航海图需要解决的关键问题,为开展编制北极航海图的深入研究奠定了一定的基础。     

基于航海应用的海图数据库比例尺分级研究

介绍了我国海图生产现状及基于数据库的海图制图技术,针对以航海图生产为主要目的的海图数据库建设中的比例尺分级问题,依据统一的样本海图选择原则,计算海部要素载负量,计算结果表明,海图载负量数值受地形、人为等因素影响大。定义一个全水深的理想海部区域,通过确定水深注记间距和载负量之间的关系、参考现有海图水深注记最小间距值和航海应用对海图比例尺分级的需求等因素,最终确定了海图数据库比例尺分级方案。     

Combined Sea Surface Determination Based on Various Geometric and Dynamic Techniques

Abstract

The combined use of Global Positioning System (GPS) differential positioning as well as ERS‐1 altimeter data is considered in implementing geodetic vertical datums and their unification. The article describes concepts, techniques, practical realization, and associated questions and problems. Particular aspects in view of small sea surface perturbations in offshore areas in determining sea surface components (variable and steady state) are discussed. The combinations of tide gauge data with altimetry and (mainly) GPS positioning for geodetic purposes are discussed in detail. Special attention is devoted to the associated reference systems as well as to the combination of dynamic (level and nonlevel surfaces) with geometric quantities. The discussion is based on a specific ERS‐1 project supported by the National Science Foundation. Implications and practical impact of the project are outlined.     

传统海图和电子海图一体化数据模型的构建与应用研究

针对国内在一定时期内既要生产传统纸质海图保证传统导航,又要生产电子海图满足电子导航的需求,构建了一个能够包容S-57电子海图和传统海图信息全集的一体化海图数据模型,基于此模型分析了两种数据到一体化数据模型的转换机制,并应用此模型开发原型系统,实现了二者之间的一体化组织和切换显示,为探索传统海图和电子海图的数据融合提供了思路和参考。     

矢量海图通告改正自动处理方法研究

在分析了国内外矢量海图通告改正技术现状的基础上,重点研究了实现矢量海图通告改正所必需的通告符号与海图要素自动转换、改正位置自动计算、改正要素自动匹配等自动处理方法,并举例说明了矢量海图通告改正的自动处理过程。     

基于A~*算法的海底地形等深线模型构建方法研究

介绍了DEM原理和构建方法,利用现有矢量海图中的水深要素及海岸线岛屿要素,对生成电子海图海底规则网格数据进行研究。计算机辅助虚拟三维海底地形,运用线性八叉树场景进行分解寻求其规律性,用A*算法最好最优地勾绘出等深线,从而建立海底地形等深线模型,为实现电子海图海底三维可视化奠定了基础。最后对算法进行分析与完善。     

新一代电子航海图面图案结构的SVG表达

针对电子航海图现行符号标准S-52难以利用和扩展的问题,分析研究了S-52标准中面图案的结构表达方法,提出了两种新方案:一是基于SVG的电子航海图面图案结构表达方法,二是基于SVG与XML参数的电子航海图面图案结构表达方法。最后,按照第二种方案,实现了S-52面图案的重构和转换,构建了完整的电子航海图面图案符号集合。     

海事测绘资料管理系统设计与实现

主要讨论了海事测绘资料管理系统中的三个主要模块：航海图书资料系统、专题测绘系统、电子文档系统的设计与实现,该系统通过对海图编绘过程中涉及到的纸质资料、电子文档资料及测绘基础数据进行系统管理,达到减少测绘工作量,提高海图编绘质量的目的。     

Accuracy assessment of GPS/Acoustic positioning using a Seafloor Acoustic Transponder System

The accuracy of GPS/Acoustic positioning is crucial for monitoring seafloor crustal deformation. However, the slant range residual is currently the only indicator used to evaluate the precision of positioning seafloor transponders. This study employs a unique Seafloor Acoustic Transponder System (SATS) to evaluate the accuracy of GPS/Acoustic seafloor positioning. The SATS has three transponders and an attitude sensor in a single unit, which provides true lengths of transponder baselines and true attitude of the SATS to ensure assessment reliability and validity. The proposed approach was tested through a GPS/Acoustic experiment, in which an off-the-shelf acoustic system was used to collect range measurements. Using GPS/Acoustic geodetic observations, the positions of three transponders on the SATS were estimated by an optimization technique combined with ray-tracing calculations. The accuracy of the GPS/Acoustic seafloor positioning is assessed by comparing the true baselines and attitude with the results derived from the position estimates of the three transponders. A sensitivity analysis is conducted to investigate the robustness of the GPS/Acoustic positioning results to changes of sound speed. Experimental results demonstrate that the use of the SATS can help to assess the validity of the GPS and acoustic travel time measurements in the GPS/Acoustic seafloor positioning.     

对中国沿海RBN-DGPS系统升级意见的商榷

依据GPS现代化的新近发展,论述了用包括4个民用测距码的三个GPS导航定位信号,船舰只需用一台GPS信号接收机就可以实现精度为±3．66m的在航三维定位测量;同时阐述了用中国的CNSS系统、俄罗斯的GLONAASS系统和欧盟的Galileo系统的三个民用导航定位信号作定位测量,能够用其无电离层效应影响的站星距离,解算出精度为±1m左右的三维位置;而不必要花巨资去升级“中国沿海RBN—DGPS系统”。     

Satellite Remote Sensing as a Reconnaissance Tool for Assessing Nautical Chart Adequacy and Completeness

National hydrographic offices need a better means of assessing the adequacy of existing nautical charts in order to plan and prioritize future hydrographic surveys. The ability to derive bathymetry from multispectral satellite imagery is a topic that has received considerable attention in scientific literature. However, published studies have not addressed the ability of satellite-derived bathymetry to meet specific hydrographic survey requirements. Specifically, the bathymetry needs to be referenced to a chart datum and statistical uncertainty estimates of the bathymetry should be provided. Ideally, the procedure should be based on readily-available, low-cost software, tools, and data. This paper describes the development and testing of a procedure using publicly-available, multispectral satellite imagery to map and portray shallow-water bathymetry in a GIS environment for three study sites: Northeast United States, Nigeria, and Belize. Landsat imagery and published algorithms were used to derive estimates of the bathymetry in shallow waters, and uncertainty of the satellite-derived bathymetry was then assessed using a Monte Carlo method. Results indicate that the practical procedures developed in this study are suitable for use by national hydrographic offices.