The SDTS Topological Vector Profile

Because the Spatial Data Transfer Standard (SDTS), also Federal Information Processing Standard 173, is designed to support any type of spatial data, implementing all of its options at one time is impossible. Instead, the SDTS is implemented through the use of profiles, which are limited subsets of the SDTS. The first profile developed is the Topological Vector Profile. This profile supports geographic vector data with geometry and topology. It does not support raster data, graphic representation modules, and geometry-only vector data. This profile was tested in 1992 in order to validate it. It will be submitted to the National Institute of Standards and Technology as an amendment to the SDTS.     

The Spatial Data Transfer Standard (FIPS 173): A Management Perspective

The Spatial Data Transfer Standard (SDTS) was approved by the Department of Commerce as Federal Information Processing Standard (FIPS) 173 on July 29, 1992. As a FIPS, the SDTS will serve as the national spatial data transfer mechanism for all federal agencies and will be available for use by state and local governments, the private sector, and research organizations. FIPS 173 will transfer digital spatial data sets between different computer systems, making data sharing practicable. This standard is of significant interest to users and producers of digital spatial data because of the potential for increased access to and sharing of spatial data, the reduction of information loss in data exchange, the elimination of the duplication of data acquisition, and the increase in the quality and integrity of spatial data. The success of FIPS 173 will depend on its acceptance by users of spatial data and by vendors of spatial information systems. Comprehensive workshops are being conducted, and the tools and procedures necessary to support FIPS 173 implementations are being developed. The U.S. Geological Survey, as the FIPS 173 maintenance authority, is committed to involving the spatial data community in various activities to promote acceptance of FIPS 173 and to providing case examples of prototype FIPS 173 implementations. Only by participating in these activities will the members of the spatial data community understand the role and impact of this standard.     

Conversion of a U.S. Geological Survey DLG-3 Data Set to the SDTS Topological Vector Profile

The Digital Line Graph level 3 (DLG-3) is the term for U.S. Geological Survey digital spatial data stored in vector form. Prior to the approval of the Spatial Data Transfer Standard (SDTS) as a Federal Information Processing Standard (FIPS), a system was developed to convert a DLG-3 data set to a sample SDTS transfer. The specifications of the SDTS Topological Vector Profile were used for the transfer (U.S. Geological Survey 1992). The process required expertise in cartography, geography, and computer science. Analysis revealed requirements for processes to transform spatial addresses, to translate and map DLG-3 spatial objects and attribute pairs to the SDTS, to compile data not available in computer-readable form, and to convert files to FIPS 123 (ISO 8211) standard. Mapping data to the SDTS proved to be complex and highlighted the need for appropriate training with regard to the SDTS and FIPS 123. Several issues were raised, such as the source of data quality information, platforms supported by the FIPS 123 Function Library software, and attribute translation criteria.     

Design of a Spatial Data Transfer Processor

A processor to support the Spatial Data Transfer Standard (NIST 1992) is being designed. The Spatial Data Transfer Processor will support both encoding and decoding operations. The system will have five components: transfer manager, content encoder, format encoder, content decoder, and format decoder. No component will have expertise in more than one area. The system design should be used as a guide when developing software for the SDTS. NOTE: Readers should be familiar with mapping concepts described in the article “An Implementation Strategy for SDTS Encoding,” located elsewhere in this issue.     

The Spatial Data Transfer Standard: A Catalyst for Change

The Spatial Data Transfer Standard (SOTS), as a standard, is somewhat of a paradox. Standards help to establish order and promote stability. As such, SDTS serves both as a standard and a catalyst for change. Beyond being the first major geographic information systems(GIS) standard, SOTS has invoked—and continues to invoke—significant changes throughout federal organizations and other' organizations that interact with them. The changes inspired by SDTS focus attention on the importance of GIS standards. This importance, in turn, is the underlying force in creating a GIS standards infrastructure. The infrastructure provides a mechanism/process for developing, approving, and coordinating GIS standards in the federal, national, and international communities.     

Cartography/Geographic Information Systems at Southwest Texas State University

Australia and New Zealand are adopting the Spatial Data Transfer Standard (SDTS) as their transfer standard for geographic data. The standard requires a number of modifications to suit Australia/New Zealand requirements. These modifications primarily involve coordinate reference systems for each country, references to those standards applicable to each country and new spatial feature dictionaries. For other countries adopting SDTS, future revisions to the standard should emphasize a framework for required modifications. Australia/New Zealand have established a support body to ensure the smooth introduction of the standard within these countries. This commercial venture has been successful in promoting the standard, in providing training and in related consulting work. The US Geological Survey has been the maintenance authority for the standard. It is essential that this function continues to be provided through this body to guarantee a single interpretation of the standard.     

An Implementation Strategy for SDTS Encoding

Any implementation plan for the Spatial Data Transfer Standard (NIST 1992) must include the following minimum set of tasks: conceptual, logical, and format level mappings; verification of the mappings; and systems development. These tasks are used as a guide in formulating specific project plans. For a data producer to implement an encoding capability, the tasks are learning the SDTS, conceptual mapping, module mapping, building sample modules, format mapping, encoding a sample data set, and developing the system. NOTE: This article assumes familiarity with the SDTS constructs of modules, fields, and subfields and the relationship of the SDTS to ISO 8211 (American National Standards Institute 1986).     

Opportunities for Use of the Spatial Data Transfer Standard at the State and Local Level

Dramatic changes in the way that spatial data have been collected and processed over that last 20 years is leading to a rethinking and restructuring on the most efficient ways to handle geographical information. These changes are taking place at the federal, state, and local governmental levels with great potential for the private sector as well. The formal adoption of the Spatial Data Transfer Standard (SDTS) as the federal database transfer standard for spatial databases signals a new era in this long chain of developments. It offers more flexible and efficient database transfers than earlier tools, and will become the workhorse for implementing the new National Spatial Data Infrastructure. It offers organizations a standard that will make possible and practical a much wider sharing of databases than is currently being done today. Use of the SDTS presents an opportunity to many organizations to share data more easily and reduce the duplication of expensive spatial database resources.     

Implementation of the Spatial Data Transfer Standard in the Commonwealth of Virginia

Present efforts to implement the Spatial Data Transfer Standard (SDTS) within the Commonwealth of Virginia are centered in Virginia's Council on Information Management (CIM). Since 1992, mapping, surveying and land information systems activities have been identified as a responsibility of the Council "The promotion of access to federal and other digital data banks through standards" is an area of CIM interest specified in the Code of Virginia. Prior to adoption of the SDTS by Virginia in November 1994, a Technical Advisory on the SDTS was issued and a SDTS Training and Education Plan was adopted. The Council on Information Management has worked with the USGS SDTS Task Force in developing this plan.     

An Overview of FIPS 173, The Spatial Data Transfer Standard

The Spatial Data Transfer Standard (SDTS), after nine years of development, was approved on July 29, 1992, as FIPS Publication 173. The SDTS consists of three distinct parts. Part 1 is concerned with logical specifications required for spatial data transfer and has three major components: a conceptual model of spatial data, data quality report specifications, and detailed logical transfer format specifications for SDTS data sets. Part 2 provides a model for the definition of real-world spatial features, attributes, and attribute values and includes a standard but working and expandable list with definitions. Part 3 specifies the byte-level format implementation of the logical specifications in SDTS Part 1 using ISO/ANSI 8211 (FIPS 123), a general data exchange standard.     

虚拟格网化的BDS/GPS位置差分方法研究

针对普通用户终端定位精度无法满足特定场景的精度需求,基于局域CORS网并融合数据,生成位置改正数以修正终端位置,提高公众定位精度。经过开发服务端与终端软件进行大量测试,分析了格网生成配置的最优方案,并且进行虚拟格网实时位置差分外符合性测试。试验证明,虚拟格网位置差分能够提高普通终端定位精度,能够为公众提供平面RMS小于3 m的位置服务。     

地图数据的综合采样方法

本文从用户对地图数字化采样工艺和数据结构的需求出发,设计了“图斑——链”综合采样方法,并编写了与之相应的程序。实验结果表明,该方法操作过程简单.可直接为地籍信息系统提供标准拓扑数据结构文件,具有一定的推广应用价值。     

Matching INSPIRE Quality of Service Requirements with Hybrid Clouds

A lot of effort has been invested in Spatial Data Infrastructures (SDIs) during the last decade regarding interoperable standards for services and data. But still the scalability and performance of SDI services is reported to be crucial especially if they are accessed concurrently by a high number of users. Furthermore, laws and provisions such as the INSPIRE directive specify challenging requirements regarding the performance, availability and scalability of SDI services. This article presents a Hybrid Cloud architecture for matching INSPIRE‐related Quality of Service (QoS) requirements, without investing in rarely used hardware in advance, by occupying external third‐party resources on a pay‐as‐you‐go basis. The presented Hybrid Cloud is a composition of a local IT‐infrastructure (Private Cloud) and the computational resources of third‐party vendors (Public Cloud). The local infrastructure is laid out to handle the average main load of a service and in lasting peak times additional resources of external providers are allocated and integrated on demand into the local infrastructure to provide sufficient service quality automatically. A proof‐of‐concept implementation of the proposed Hybrid Cloud approach is evaluated and benchmarked with respect to INSPIRE‐related QoS requirements.     

Customized Visualization of Natural Hazards Assessment Results and Associated Uncertainties through Interactive Functionality

Communication of natural hazard assessment results is crucial to protect people and infrastructure from devastating impacts of extreme events. While hazard maps provide important information on potential impacts, their interpretation and the general knowledge exchange between stakeholders is often difficult. Web-based information systems contain the potential to support hazard management tasks by fast distribution and customization of hazard visualizations through interactive functionality. Cartographic principles are, however, often ignored in existing web-based visualizations which leads to poor graphical results and consequently to an impairment of the information flow. While these issues need to be solved, a new task is already waiting: the integration of uncertainty information into hazard visualizations. Since many hazard management activities rely on hazard assessment results, communication of associated uncertainties among experts is vital.

The challenge of this research is to overcome these existing shortcomings by combining high quality cartographic visualizations of natural hazard data as well as associated uncertainties with interactive functionality. The resulting web-based cartographic information system will convene the needs of natural hazard specialists by offering a high level of customization: the suggested visualizations include various cartographic techniques such as the application of textures, bars, and interpolated surfaces. The possibility to interactively select particular data sets, customize colors, choose dimensions, query attribute data, and include uncertainty information facilitates the interpretation of complex data and finally the communication among natural hazard specialists.

In this article we summarize requirements that have to be considered, suggest functionalities necessary to perform natural hazards management tasks, and present a prototype of an expert system for the visualization and exploration of natural hazards assessments results and associated uncertainties.     

Profile Development for the Spatial Data Transfer Standard

The Spatial Data Transfer Standard (SDTS), or Federal Information Processing Standard (FIPS) 173, is designed to support all types of spatial data. Implementing all of the standard's options at one time is impractical. Therefore, implementation of the SDTS is being accomplished through the use of profiles. Profiles are clearly defined, limited subsets of the SDTS created for use with a specific type or model of data and designed with as few options as possible. When a profile is proposed, specific choices are made for encoding possibilities that were not addressed, left optional, or left with numerous choices within the SDTS. Profile development is coordinated by the U.S. Geological SUIVey's SDTS Task Force. When completed, profiles are submitted to the National Institute of Standards and Technology (NIST) for approval as official amendments to the SDTS. The first profile, the Topological Vector Profile (TVP), has been completed. A Raster Profile has been tested and is being finalized for submission to the NIST. Other vector profiles, such as those for network and nontopological data, are also being considered as future implementation options for the SDTS.     

The new gravity base net 1976 of the Federal Republic of Germany (DSGN 76)

A new gravity base net (“Schweregrundnetz 1976 der Bundesrepublik Deutschland”, DSGN 76) has been established in the Federal Republic of Germany, to meet the increased requirements of geophysics, geology, metrology and geodesy. The net comprises 21 stations with three excenters each. The gravity values were determined using 4 absolute stations, 11 IGSN71-stations and about 3000 relative gravity meter observations with 4 gravity meters. Instrumental investigations and special treatment of local tidal and atmospheric effects improved the data for the least squares adjustment, which was performed by the method of observation equations following the use of condition equations. The final adjustment showed a point r.m.s. error of about 10μGal[10^?8 ms^?2]. Detailed results will be published in the ”Veröffentlichungen der Deutschen Geodätischen Kommission”.     

A Cadastral Geodatabase for the U.S. Fish and Wildlife Service

The U.S. Fish & Wildlife Service Cadastral Data Working Group, comprised of cartographers and GIS specialists from all management regions, has produced a state-of-the-art database that stores data for all interests in real property in the U.S. National Wildlife Refuge System. The FWS Cadastral Geodatabase provides an integral component of the Refuge Lands Geographic Information System (RLGIS) by supplying boundary and parcel information to the biological geodatabases currently within the RLGIS data model. Cadastral data describes the past, current, and future right, title and interest in real property, including the spatial information necessary to describe the geographic extent. The geodatabase is the common data storage format for geographic features and attributes. A consistent and accurate cadastral geodatabase that is common across the nation and can be shared between management regions enables users to leverage the spatial data to its full potential. A web mapping application has been built utilizing the FWS cadastral geodatabase, allowing a non-GIS user to view the FWS managed lands and waters.     

SVLBI用于大地测量的卫星轨道及其跟踪网设计

SVLBI （space very long baseline interferometry） has some important potential applications in geodesy and geodynamics, for which one of the most difficult tasks is to precisely determine the orbit of an SVLBI satellite. This work studies several technologies that will possibly be able to determine the orbit of a space VLBI satellite. Then, according to the types and charac- teristics of the satellite and the requirements for geodetic study and the geometry of the GNSS （GPS, GALILEO） satellite to track the space VLBI satellite, the six Keplerian elements of the SVLBI satellite （TEST-SVLBI） are determined. A program is designed to analyze the coverage area of space of different altitudes by the stations of the network, with which the tracking network of TEST-SVLBI is designed. The efficiency of tracking TEST-SVLBI by the network is studied, and the results are presented.     

面向对象标准最邻近分类法在地理国情监测中的应用

地理国情监测项目范围大,遥感影像分辨率高,信息提取精度要求高,人工解译任务繁重,急需利用自动解译技术来提高效率。面向对象的标准最邻近分类法可针对地表覆盖信息实现数据的自动快速提取,相比于人工分类方法所提取的结果,该方法具有较高的精度,并且可大幅度提高地理国情监测地表覆盖信息提取的生产效率。