A Validation of MODIS Snowcover Products in Romania: Challenges and Future Directions

The MODIS snowcover product is one of many geophysical products derived from MODIS data. A cross‐validation of the MODIS snowcover daily products with data obtained from the meteorological network stations was conducted for the entire territory of Romania. The validation time interval covered the period between 29 October, 2004 and 1 May, 2005. The overall accuracy for the whole set of cloud‐free useful data proved to be 95%. The validation time interval included the three common snow situations: (1) late autumn months where 37.1% of the initial set of the data was used, and the overall accuracy was 98.6%; (2) the “winter” months where the clouds reduced the set of useful data – 31.75%– and the overall accuracy was 93.7%; and (3) the months of February and March which returned the highest accuracy (> 95%). Additionally, a cross‐validation using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) high‐resolution imagery was carried out. Furthermore, the MODIS, meteorological data and ASTER data were integrated into a Geographic Information System (GIS) environment to perform flexible and comprehensive cross‐checking followed by a thematic analysis based on additional sets of data such as digital elevation models (DEMs) and land‐cover datasets.     

A Distributed Geoprocessing Concept for Enhancing Terrain Analysis for Environmental Modeling

Geographic Information Systems (GIS) are well suited to support environmental modeling for dealing with space. However, some of the limitations of current GIS are the lack of tools for comprehensive documentation of the models, the inadequate representation of fields, and the deficient methodology for comprehensive management of uncertainty. Using Digital Terrain Modeling and Analysis as an example, this paper proposes an enhanced approach to overcome these drawbacks. It suggests implementing sophisticated functionality for modeling and analysis of fields in special-purpose modules outside monolithic GIS. These modules include three components: (1) an extensive framework for metainformation that allows a sound assessment of the fitness-for-use of digital field representations for environmental modeling applications, (2) an explicit digital representation of the field phenomenon equipped with the appropriate tools for the derivation of data, and (3) the methods to assess the quality of derived data. A standardized interface enables communication between the module and other software components. The presented modular approach combines the functionality of common GIS with highly specialized modeling and analysis tools encapsulating expert knowledge about the represented phenomena.     

Requirements for Next Generation Spatial Data Infrastructures-Standardized Web Based Geoprocessing and Web Service Orchestration

Spatial Data Infrastructures (SDI) have been widely accepted to exchange geospatial data among organizations. Today SDIs main focus lies on the provision of geospatial data in the form of distributed spatial web services, the retrieval through catalogues, and visualization in the form of Web Map Services (WMS). The hypothesis presented in this paper takes SDI's one step further by providing a method to process geodata in an Open Geospatial Consortium (OGC) compliant way into information. Two case studies present the potential of standardized geoprocessing services. In addition, this paper addresses the problem of service chaining by providing a system architecture to implement complex geoprocessing models and workflows based on web services using Web Service Orchestration (WSO). The proposed methods utilize spatial standards provided by OGC, the International Organization for Standardization (ISO) and ‘mainstream IT’ standards provided by the World Wide Web Consortium (W3C) and the Organization for the Advancement of Structured Information Standards (OASIS) to establish a generic web service architecture for providing common geoprocessing capabilities (e.g. spatial algorithms, map algebra, etc.) for usage in SDIs.     

A Service Oriented Geoprocessing System for Real‐Time Road Traffic Monitoring

The emergence of the Sensor Web has paved the way for a new set of innovative software applications that exploit the enhanced availability of real‐time information. This article describes one such application built from Sensor Web components that aggregates GPS track data from a fleet of vehicles to provide an overview of road traffic congestion at the city scale. The application embodies a Service Oriented Architecture; web service components are used to archive and pre‐process incoming sensor observations, to encapsulate a horizontally partitioned spatial database that performs geoprocessing, and to disseminate results to client applications. Our results confirm that floating car data can provide an accurate depiction of current road traffic conditions. The presented solution uses Open Geospatial Consortium web services where possible and serves to highlight the difficulties inherent in achieving horizontal database scalability in sensor based geoprocessing systems.     

利用分离性测度多类支持向量机进行高光谱遥感影像分类

提出了一种基于变换域离散度排序的高光谱图像快速压缩算法。该算法针对高光谱数据在Hadamard变换域的特性,自适应地选择有利的排列顺序,将变换域光谱矢量的各维度按照离散度进行重新排序,不仅使光谱矢量的大部分能量和差异集中在低维部分,而且把高信噪比的分量调整到低维空间,并据此构造出高效的码字排除不等式,最后结合LBG(Linde Bazo Gray)聚类算法,通过矢量量化快速完成高光谱图像的编码。在不同压缩比下进行实验,结果表明,本文提出的高光谱图像压缩算法能在保证良好的图像恢复质量的前提下,大幅度降低计算复杂度,实现快速压缩。     

高光谱目标探测的进展与前沿问题

针对高光谱目标探测问题的主要挑战,将高光谱目标探测的进展与前沿问题分为两个方面进行综述。基于信号检测理论的方法如结构化背景的约束能量最小化方法、非结构化背景的自适应一致性余弦评估器等,是高光谱目标的探测经典算法;随着统计模式识别与机器学习领域中新技术的出现,一些数据驱动的目标探测方法逐渐成为了高光谱目标探测的前沿问题,如核方法、稀疏表达方法等。概述了两类方法的特点,比较了各自的优势和不足,并展望了高光谱目标探测未来的发展趋势。     

试论中国NSDI建设的若干问题

国家空间数据基础设施(National Spatial Data Infrastructure,简称NSDI)是"数字地球"的基础.要发展中国数字地球及其应用,就必须加大NSDI的建设力度.文中主要从(地球)空间数据框架、空间数据标准、空间数据交换网络和空间数据协调管理机构4个方面,介绍了中国NSDI的有关进展,分析了其中存在的一些问题,讨论了发展方向.     

基于Web Service的分布式遥感影像数据库设计与实现

结合实际工作中影像数据存储与管理的需求,在应用Web Service技术对遥感图像分布式处理的过程中,就不同形式的数据库查询方法对遥感影像数据进行基于元数据库的数据库系统设计,并结合SOAP调用等技术对其进行原形实现。从数据库的各种基本操作可以看出,基于SOAP/XML技术及辅助元数据库的分布式影像数据库设计方法及远程调用在实际工作需求中是有效的。     

试论中国NSDI建设的若干问题

国家空间数据基础设施是“数字地球”的基础。要发展中国数字地球及其应用,就必须加在ＮＳＤＩ的建设力度,文中主要从（地球）空间数据框架,空间数据标准,空间数据交换网络和空间数据协调管理机构４个方面,介绍了中国ＮＳＤＩ的有关进展,分析了其中存在的一些问题,讨论了发展方向。     

面向未来的智慧农业气象精细化服务系统的设计

针对我国当前农业气象服务模式中存在的产品粗放,服务手段单一,基层农气服务人员及农气专家参与程度低,缺乏为农户尤其是农业大户提供精细化、个性化、专业化的产品服务能力,因而不能很好地满足山地丘陵地区农业气象服务的需求等问题,本文设计了一种新型的农业气象精细化智能服务模式.该模式既考虑到方便、快捷地收集用户的个性化服务需求信息,又考虑到不增加业务工作人员的投入,设计了方便的系统和工具,吸引农业气象业务工作人员、基层农业气象服务人员、农技专家等多方协作参与,实现了信息互联共享,高效智能地为农业生产企业或个人提供精细化、智慧化、专业化的农业气象服务,并在重庆成功地进行了试点应用.结果表明,该模式能够较好地解决重庆地区的精细化、智慧化和专业化的农业气象服务方面的需求.     

分布式体系结构下的地理信息服务的分层协议架构

分布式体系结构的出现以及物联网的建设使地理信息服务的发展出现新一次飞跃,这为地理信息服务带来了新的机遇。本文回顾了地理信息服务的发展,论述了地理信息服务在分布式条件下可能发生的新变化,基于对计算机网络体系结构TCP/IP协议集的研究,提出了为未来的分布式地理信息服务体系建立的一种分层协议架构,从而促进地理信息服务的标准化、体系化,加速全民地理信息服务体系的建设。     

智能时代测绘与位置服务领域的挑战与机遇

由人工智能引发的智能革命星火,正向各行各业蔓延,测绘与时空位置服务的相关方法、技术、产业形态和商业模式所面临的挑战与机遇,是值得深入思考的问题。从人工智能的内涵、历程和趋势出发,阐述了对新一代人工智能特征的理解,并对智能时代来临所带来的机遇和挑战进行了分析。聚焦到测绘与位置服务领域,认为其作为行业,不会消失但必须转型,并分析了转型的可能路径;作为学科,不会扩张但须跨界、交叉和融合;作为职业,将会出现蓝领消失,创客、智士领军的局面。测绘与位置服务行业需要充分挖掘自身优势,将系统性思维、时空观思维和创意性思维作为开启智能时代大门的钥匙,才能实现测绘与位置服务行业向绿色、智能、泛在发展的整体转型。     

分布式空间信息网络服务安全架构的设计与实现

从网络信息安全的一般性问题入手,研究了以多层网络服务结构为核心、网络安全传输算法为基础、授权管理、监控审计和身份认证为辅助,同时兼顾性能、并具扩展性的分布式空间信息网络服务安全架构;并以多种比例尺地理空间矢量数据、高分辨率卫星影像数据和各种专题数据为数据源,建立了高质量、高稳定性和高可靠性的空间信息网络服务系统;解决了地理空间数据共享与网络服务安全的矛盾,为应用部门提供地理空间信息查询和分析服务,具有重要的使用价值和现实意义.     

分布式空间信息网络服务安全架构的设计与实现

从网络信息安全的一般性问题入手,研究了以多层网络服务结构为核心、网络安全传输算法为基础、授权管理、监控审计和身份认证为辅助,同时兼顾性能、并具扩展性的分布式空间信息网络服务安全架构;并以多种比例尺地理空间矢量数据、高分辨率卫星影像数据和各种专题数据为数据源,建立了高质量、高稳定性和高可靠性的空间信息网络服务系统;解决了地理空间数据共享与网络服务安全的矛盾,为应用部门提供地理空间信息查询和分析服务,具有重要的使用价值和现实意义。     

Map Symbols for Crisis Mapping: Challenges and Prospects

Crisis maps and visualizations utilized routinely by international agencies, humanitarian organizations, and non-governmental organizations for aid and relief activities commonly require complex sets of map symbols. However, effective map symbology for humanitarian relief purposes entails several challenges, including consideration of the following: (1) taxonomy development, (2) symbol design issues, (3) promulgation and sharing of map symbols, and (4) standardization of symbols within and among organizations. This paper discusses these key challenges to the design and use of crisis map symbology through a review of the cartographic literature as well as results collected from a survey targeted at humanitarian organizations from around the world. The survey was designed to gather information on current symbology design and use practices in order to understand common challenges. Survey results confirm agreement in the persistence of these four primary symbology challenges, especially the importance of intuitive symbol design. Respondents disagreed most about the adequacy of current crisis map symbology standards as well as the ease in which standards may be implemented within and across organizations. Survey results suggest the need for expert systems designed specifically for symbology design to support humanitarian relief activities.     

基于云计算的分布式切图服务设计与实现

云计算如何在GIS领域真正落地,传统GIS技术如何改变才能适应形势,并真正将云计算和云平台的优势为自己所用,是当前云GIS最重要的研究课题。传统GIS地图服务中,地图缓存是基于单机预先切好的地图瓦片,并通过单机对外提供。这种传统的切图技术,对计算资源的利用率较低,且海量数据切图时间长达数月甚至数年,严重影响工作效率,加之没有故障恢复机制,切图任务一旦出现故障,整个切图工作都要推倒重来。在云计算快速发展的形势下,如何利用云平台的优势,提升海量地图数据的切图效率和稳定性,就成为云GIS迫切需要解决的问题。本文在分析云计算技术优势的基础上,对传统切图技术进行了改进,提出了分布式切图服务的设计思路,实现了地图瓦片的分布式生成、管理与发布,对比测试证明,分布式切图的性能、稳定性较传统方式有明显提升。基于此种设计实现的SuperMap iServer Java 6R(2012)分布式切图模块,支持地图瓦片的分布式切片和分布式存储管理,支持多种分布式文件系统、NAS与大数据存储系统(如FastDFS、EMC Isilon等),进一步提升了地图瓦片的存取速度和支持的并发数。本文提出的分布式切图技术,是对传统地图缓存方式的创新,为云GIS提供了一定的研究基础。     

基于流计算的分布式地理信息服务监控框架设计与实现

服务监控、故障溯源和服务日志的统计分析,是数字城市地理信息公共服务平台和智慧城市时空信息云平台的重要能力,能够为平台的稳定运行提供可靠保障.本文分析了现有地理信息服务监控方案的局限性,引入了ELK日志框架和Kafka Streams流计算框架,并对地理信息服务特性进行优化,设计和实现了一种分布式地理信息服务监控框架.多地的应用实践表明,该框架实现了海量服务日志数据的采集、处理、存储和多维度快速检索,解决了传统集中式日志数据库写入性能差、扩展困难、查询统计效率低和商业GIS软件服务兼容性差等问题,满足了GIS平台的统一运维、统计分析和监管需要.     

基于Web Service的电子地图分布式数据发布与多级链接

越来越庞大的数据浏览量对电子地图的部署方式提出了更高的要求.传统的电子地图数据往往以切片的形式集中存放于服务器.为了提高电子地图部署的灵活性,分布式数据部署越来越多地应用到电子地图网站建设中.以Web service为技术基础,讨论电子地图分布式数据发布与多级链接方法;并将Web service与Ajax技术相配合,实现了电子地图分布式数据发布与多级链接的功能.     

湖北省测绘成果分发服务模式的初步建设

作为"数字湖北"地理空间框架应用展示系统之一的湖北省测绘成果分发服务系统,实现了分发服务模式的系统化成果,为"数字湖北"面向公众更加深入的服务提供了坚实的保障,并为分发服务体系的建立指明了方向。