The Roles of Web Feature and Web Map Services in Real-time Geospatial Data Sharing for Time-critical Applications

Many time-critical applications such as emergency response, location-based services, and real time traffic management need instant access to diverse data to make quick decisions and take instantaneous actions. However, two issues block time-critical applications to quickly acquire and integrate spatial data over the web: (1) the heterogeneity of existing GIS systems, and (2) the file-level data sharing systems over the web. This research examines current open standards, protocols, and technologies capable of solving the two issues for real-time spatial data sharing over the web. Focusing on investigating the role of Web Feature Services (WFS) and Web Map Services (WMS), this research has developed a solution for real-time geospatial data sharing at the feature level over the web. A prototype has been implemented to query, extract, create, delete, update, and map geographic features stored in web-accessible OGC (Open Geospatial Consortium) simple feature datastores for transportation emergency applications. The prototype results show that the OGC WFS and WMS play important roles in real-time geospatial data sharing and exchange from heterogeneous sources at the feature level for time-critical applications. The WFS and WMS eliminate time-consuming data translation and facilitate reuse of existing geospatial data over the web. Several issues related to the solution are also discussed in the paper.     

Hypercube-Based Visualization Architecture for Web-Based Environmental Geospatial Information Systems

The geospatial field significantly influences the development of the environmental domain, including a wide range of geospatial and cartographic information systems, such as Geographic Information Systems (GIS), Multimedia Atlas Information Systems (MAIS) and more recently web-based GIS (Web-GIS). In this context, we introduce web-based environmental geospatial information systems (Web-EGIS) as a special case of Web-GIS, aiming to integrate the functionalities of geospatial information systems with the enormous quantity of specialized, distributed and highly heterogeneous environmental geo-referenced data and services. We define three main characteristics of the Web-EGIS. The first is a generic hypercube-based data organization and visualization. The next characteristic is a standard-based, three-tier service-oriented architecture. The third and last characteristic is the traceability of the architectural and design decisions, for which we introduce the new concept of an ‘Environmental Application Context’, arguing that not only the functional but also the non-functional requirements (NFRs) have an important role in defining the architecture, software components and data services of such systems. In a nutshell, a Web-EGIS is characterized by a coherent user experience through the hypercube-based visualization concept, technically supported by a service-oriented architecture that is structured according to an extensive analysis of NFRs. On this basis, we introduce the Geodata visualization and interactive training environment (GeoVITe) Platform for Interdisciplinary Environmental Research as a reference implementation of a Web-EGIS with its basic design requirements, integrative hypercube-based visualization for heterogeneous data sources, extended web cartography functionalities, and its de facto system architecture. The concept of the hypercube-based visualization is better transferred to the system architecture by understanding the ‘Environmental Application Context’ of this particular Web-EGIS, which also makes it easier to maintain and enhance. The resulting system is a support platform for research activities in the environmental domain.     

全国警用空间信息服务互联互通的关键技术

针对大型空间信息服务平台构建过程中的数据互联互通和信息集成问题,从集成框架体系结构、技术路线和关键技术3个方面进行研究,提出了分布式地理空间信息集成框架的5层体系结构模型和原子空间信息服务概念;通过研究分布式空间查询路由算法和虚拟四叉树模型等关键技术,探索实现分布式环境下的空间信息的互联互通。     

基于Spark的分布式空间数据存储结构设计与实现

Apache Spark分布式计算框架可用于空间大数据的管理与计算,为实现云GIS提供基础平台。针对Apache Spark的数据组织与计算模型,结合Apache HBase分布式数据库,从分布式GIS内核的理念出发,设计并实现了分布式空间数据存储结构与对象接口,并基于某国产GIS平台软件内核进行了实现。针对点、线、面数据的存储与查询,与传统空间数据库系统PostGIS进行了一系列对比实验,验证了提出的分布式空间数据存储架构的可行性与高效性。     

Automatic search of geospatial features for disaster and emergency management

Although the fast development of OGC (Open Geospatial Consortium) WFS (Web Feature Service) technologies has undoubtedly improved the sharing and synchronization of feature-level geospatial information across diverse resources, literature shows that there are still apparent limitations in the current implementation of OGC WFSs. Currently, the implementation of OGC WFSs only emphasizes syntactic data interoperability via standard interfaces and cannot resolve semantic heterogeneity problems in geospatial data sharing. To help emergency responders and disaster managers find new ways of efficiently searching for needed geospatial information at the feature level, this paper aims to propose a framework for automatic search of geospatial features using Geospatial Semantic Web technologies and natural language interfaces. We focus on two major tasks: (1) intelligent geospatial feature retrieval using Geospatial Semantic Web technologies; (2) a natural language interface to a geospatial knowledge base and web feature services over the Semantic Web. Based on the proposed framework we implemented a prototype. Results show that it is practical to directly discover desirable geospatial features from multiple semantically heterogeneous sources using Geospatial Semantic Web technologies and natural language interfaces.     

Integrated Mobile GIS and Wireless Internet Map Servers for Environmental Monitoring and Management

With the progress of mobile GIS technology there is a great potential for adopting wireless communications and Internet mapping services for regional environmental management programs and natural habitat conservation. This paper provides an overview of a NASA-funded research project that focuses on the development of mobile GIS tools and wireless Internet Map Server (IMS) services to facilitate environmental monitoring and management tasks. By developing and testing wireless web-based map/image servers, mobile GIS applications, and global positional systems (GPS), this research created an integrated software/hardware infrastructure for a prototype mobile GIS application. The mobile GIS prototype allows multiple resource managers and park rangers to access large-size, remotely sensed images and GIS layers from a portable web server mounted in a vehicle. Users can conduct real-time spatial data updates and/or submit changes back to the web server over the wireless local area network (WLAN). This paper discusses in general the major components of mobile GIS, their current technological limitations, and potential problems during implementation. Key research agenda for mobile GIS are identified with suggestions for future research and development.     

面向"人"的地学可视化探讨

面向"人"地学可视化中的"人".主要从地学可视化系统的使用者(简称"应用人"),从地学可视化要表达的地球表层系统地理环境中的社会人(简称"社会人").以及从作为能地理认知与思维、能表达/传递地理知识及知识创新的"人"(简称"知识人")3个方面定义.从上述3个方面建立了面向"人"的地学可视化概念框架.在面向"应用人"方面,主要介绍了协同可视化以及自我参照可视化;在面向"社会人"方面,主要阐述个体日常行为时空路径可视化、群体行为模拟可视化,以及社会关系网络可视化;在面向"知识人"方面,主要讨论知识可视化.本文最后从本体框架、信息采集与获取技术、数据组织与表达模型、可视化表达方法、主体概念方面,对于面向"人"GIS以及可视化的关键问题与技术进行了探讨.     

gvSOS: A New Client for the OGC® Sensor Observation Service Interface Standard

A key problem with sensor networks is achieving interoperability between different networks potentially built using different software and hardware platforms. Services interfaced by the Open Geospatial Consortium (OGC) specifications allow GIS clients to access geospatial data without knowing the details about how these data are gathered or stored. Currently, OGC is working on a set of interoperable interfaces and metadata encodings known as Sensor Web Enablement (SWE) that enables the integration of heterogeneous sensor systems and measurements into geospatial information infrastructures. In this article we present the implementation of gvSOS, a new module for gvSIG to connect to Sensor Observation Services (SOS). The gvSOS client module allows gvSIG users to interact with SOS servers, displaying the information gathered by sensors as a layer composed by features. We present the software engineering development process followed to build the module. For each step of the process we specify the main obstacles found during the development such as restrictions of the gvSIG architecture, inaccuracies in the OGC specifications, and a set of common problems found in current SOS server implementations available on the Internet. For most of the problems found we propose a solution, or at least we present a path that might lead to it.     

GeoScope: Full 3D geospatial information system case study

Aiming at the integrative management and comprehensive applications of large-scale 3D geospatial information covering the full 3D space of a city,this paper briefly introduces the design and implementation of a full 3D GIS platform:GeoScope,which provides a professional solution for the massive full three-dimensional geospatial data integration,management,analysis,visualization,and applications.GeoScope is characterized by:(1) extendible software architecture based on the hierarchical message bus,facilitates multimodal integrative applications of 2D GIS and 3D GIS;(2) unified 3D city models,support multiscale semantic representation of outdoor & indoor and aboveground & underground 3D objects;(3) high-efficient 3D geospatial database engine,supports integrated management of massive 3D geospatial data for real-time applications;and (4) high-performance visualization engine exploiting the massively parallel computation architecture of modern GPUs,supports real-time realistic rendering of large-scale complicated 3D geospatial environments.The successful pilot application of GeoScope is also illustrated with the 3D city models of 8494 km2 of the whole Wuhan City,the largest city in middle China.     

Asynchronous Geospatial Processing: An Event‐Driven Push‐Based Architecture for the OGC Web Processing Service

Geospatial processing tasks like solar potential analyses or floodplain investigations within flood scenarios are often complex and deal with large amounts of data. If such analysis operations are performed in distributed web‐based systems, technical capabilities are mostly not sufficient. Major shortcomings comprise the potentially long execution times and the vast amount of messaging overhead that arise from common poll‐based approaches. To overcome these issues, an approach for an event‐driven architecture for web‐based geospatial processing is proposed within this article. First, this article presents a thorough qualitative discussion of different available technologies for push‐based notifications. The aim of this discussion is to find the most suitable push‐based messaging technologies for application with OGC Web Processing Services (WPS). Based on this, an event‐driven architecture for asynchronous geospatial processing with the WPS is presented, building on the Web Socket Protocol as the transport protocol and the OGC Event Service as the message‐oriented middleware. The proposed architecture allows pushing notifications to clients once a task has completed. This paradigm enables the efficient execution of web‐based geospatial processing tasks as well as the integration of geographical analyses into event‐driven real‐time workflows.     

Geospatial information service based on digital measurable image

LBS (location-based service) is a remarkable outcome of the development from GIS to geospatial information service. Faced by the requirements of geospatial information from the masses and the opportunity provided by the next generation Internet and Web 2.0, a new model of geospatial information service based on DMI (digital measurable image) is presented. First, the concept of LBS and the opportunities of Web 2.0 are introduced, then the characteristic of DMI is discussed. Taking the Image City·Wuhan as an example, the function of geospatial information service based on DMI is introduced. Finally, the feasibility for its industrialization is discussed.     

The Space Package: Tight Integration between Space and Semantics

Interpretation of spatial features often requires combined reasoning over geometry and semantics. We introduce the Space package, an open source SWI‐Prolog extension that provides spatial indexing capabilities. Together with the existing semantic web reasoning capabilities of SWI‐Prolog, this allows efficient integration of spatial and semantic queries and provides an infrastructure for declarative programming with space and semantics. There are few systems that provide indexing and reasoning facilities for both spatial and semantic data. A common solution is to combine separate semantic reasoning and geospatial services. Such loose coupling has the disadvantage that each service cannot make use of the statistics of the other. This makes optimization of such a service‐oriented architecture hard. The SWI‐Prolog Space and Semantic web packages provide a native Prolog interface to both spatial and semantic indexing and reasoning, which makes it easy to write combined query optimizers. Another advantage of the Space package is that it allows declarative logic programming, which means in practice that you say what you want to compute instead of how to compute it. The actual indexing machinery is encapsulated inside Prolog predicates. In this article we describe the interface of the Space package, compare its functionality to alternative software libraries, and show how to work with it using three example applications. These example illustrations include reasoning over movement patterns, dynamically loading geospatial linked data off the semantic web, and setting up a simple KML server.     

The framework of a geospatial semantic web-based spatial decision support system for Digital Earth

Abstract

While significant progress has been made to implement the Digital Earth vision, current implementation only makes it easy to integrate and share spatial data from distributed sources and has limited capabilities to integrate data and models for simulating social and physical processes. To achieve effectiveness of decision-making using Digital Earth for understanding the Earth and its systems, new infrastructures that provide capabilities of computational simulation are needed. This paper proposed a framework of geospatial semantic web-based interoperable spatial decision support systems (SDSSs) to expand capabilities of the currently implemented infrastructure of Digital Earth. Main technologies applied in the framework such as heterogeneous ontology integration, ontology-based catalog service, and web service composition were introduced. We proposed a partition-refinement algorithm for ontology matching and integration, and an algorithm for web service discovery and composition. The proposed interoperable SDSS enables decision-makers to reuse and integrate geospatial data and geoprocessing resources from heterogeneous sources across the Internet. Based on the proposed framework, a prototype to assist in protective boundary delimitation for Lunan Stone Forest conservation was implemented to demonstrate how ontology-based web services and the services-oriented architecture can contribute to the development of interoperable SDSSs in support of Digital Earth for decision-making.     

GeoPW: Laying Blocks for the Geospatial Processing Web

Recent advances in Web‐related technologies have significantly promoted the wide sharing and integrated analysis of distributed geospatial data. Geospatial applications often involve diverse sources of data and complex geoprocessing functions. Existing Web‐based GIS focuses more on access to distributed geospatial data. In scientific problem solving, the ability to carry out geospatial analysis is essential to geoscientific discovery. This article presents the design and implementation of GeoPW, a set of services providing geoprocessing functions over the Web. The concept of the Geospatial Processing Web is discussed to address the geoprocessing demands in the emerging information infrastructure, and the role of GeoPW in establishing the Geospatial Processing Web is identified. The services in GeoPW are implemented by developing middleware that wraps legacy GIS analysis components to provide a large number of geoprocessing utilities over the Web. These services are open and accessible to the public, and they support integrated geoprocessing on the Web.     

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.     

地理信息服务质量(QoGIS):概念和研究框架

在探讨地理数据特点的基础上，提出了地理信息服务质量（QoGIS）的概念和研究框架，设计了一个体现地理信息服务质量的原型系统架构。     

构建面向服务的汛情信息共享平台

将面向服务架构的设计原则应用到汛情信息共享平台建设中,以数字驻马店地理空间框架提供的地理信息服务数据为基础,以水利汛情信息为管理对象,借助Flex技术并结合ArcGIS Server平台,实现了汛情信息的共享与集成展示、降雨形势分析等功能,为水利部门提供了一个良好的管理规划和决策支持的Web共享平台。     

AJAX技术在地理信息服务中应用研究

GIS与Web服务的结合,为跨平台的地理信息共享和互操作提供了一种松散耦合、灵活的体系架构。而目前客户端对地理信息服务的调用大多是通过同步通讯方式工作的,客户端的每一个请求都要直接经过服务器的处理、返回并刷新整个页面,这不但加重服务器负担,占用了网络带宽,而且在服务器处理过程中,客户端无法完成其他工作。针对这种缺陷,本文将AJAX(Asynchronous JavaScript+XML)技术融入到Web服务中,并提出一种基于Ajax技术的Web应用模型,将其应用于地理信息服务中,提升了系统运行效率,改善了用户Web应用的体验。     

地理信息系统集成平台框架结构研究

提出了基于客户／服务器结构的地理信息系统集成平台总体结构,探讨了基于元数据的地理信息系统数据集成平台以建立物理上分布而逻辑上集中的分布式地理信息系统数据库,提出了应用符合３ＮＦ范式的关系数据库进行模型管理的模式,在此基础上探讨了地理信息系统可视化建模工具。