Information Rich GIS Dissemination in Disconnected Environments

Information‐rich maps are today rendered from powerful back‐end servers. Unfortunately, there may be circumstances in which access to such Internet‐resident web services is infeasible or unreliable. These disconnected environments can theoretically occur during major power outages, malicious attacks on communications infrastructure, natural disasters, or in remote operating environments. One might also envision applications in which a disconnected service is preferred over Internet‐resident services, such as when the local internet service is overloaded with traffic, making communication though it difficult. To this end, this article presents a software stack (a map stack) that can serve GIS information from low power embedded nodes. The system combines a spatially enabled SQL database, location‐based routing, and multi‐scale map rendering to serve information‐rich GIS data on common hand‐held devices at minimal energy consumption. The maps are rendered on browsers on off‐the‐shelf mobile devices such as smart phones and tablets. The system also provides a crowd sourced capability where end users can annotate maps with up‐to‐date information on the scene of the natural disaster. We have prototyped a fully functional map stack on a battery powered Gumstix Overo air platform. We show that the map stack is a highly extensible platform that provides low latency, and low energy dissemination of maps during a natural disaster.     

基于ArcGIS Server的GIS Web服务自动发布关键技术研究

Web GIS技术主要采用GIS Web服务方式对外提供资源访问和空间分析能力。GIS Web服务提高系统资源利用率,扩大信息使用范围,但GIS Web服务主要依赖于服务器端GIS平台提供的可视化工具进行后台发布,前台用户无法根据自己业务需要自动发布GIS Web服务。文中基于ArcGIS Server平台研究一种GIS Web服务自动发布方案,以双丰林业局林政资源服务系统的在线采编模块为例,阐述该案例的应用。     

The Potential of Maps APIs for Internet GIS Applications

Since the launching of Maps Application Programming Interfaces (APIs) in 2005, many web developers, including geographers and non‐geographers, applauded the freely adaptable tools and used them to spawn numerous Internet applications. The success of the Maps APIs is largely attributable to its no‐cost policy, the availability of global data coverage, dynamic navigation, query capability, and ease of implementation. Despite its versatility in dynamic exploration of geographic data online, the existing Maps APIs lack Geographic Information System (GIS) functionalities compared to other Internet Mapping Services. The goal of this research was to review the potential of the Maps APIs for Internet GIS applications. This research employed the Google Maps API and developed a web prototype that disseminates spatial information of urban sprawl in Mundy Township, Michigan. The results revealed that both vector and raster data could be effectively represented by using the Maps API. Moreover, the Geographic Markup Language (GML) approach illustrated great potential for developing Internet GIS solutions around open specifications. This research suggested several potential solutions to expand the spectrum of GIS operations of the Maps APIs by incorporating the XML‐related technology and extending the JavaScript library.     

基于WebGIS的Web服务器日志管理系统设计与实现

WebGIS优势是通过互联网对地理空间数据进行发布和应用,以实现空间数据的共享和相互操作。将WebGIS和富客户端技术引入Web服务器日志管理领域,从总体设计、数据库设计、实现框架等几个方面设计了Web服务器日志管理系统开发框架,并开发了某工业园区信息共享平台日志管理系统。该系统可以高效便捷地实现网络访问数据空间可视化、访问流量在线监控、访问数据统计与分析等功能,为Web服务器运行维护提供科学的决策依据。     

A Spatial Decision Support System for Radar-meteorology Data in South Africa

The South African Weather Service (SAWS) operates a radar station network, providing data continuity back to 1994, which is unique for southern Africa. The Geographical Resources Analysis Support System (GRASS) GIS was introduced to the SAWS “Meteorological Systems and Technology” (METSYS) radar research center in 1999 where it is still used for meteorologic research. The predominantly convective nature of precipitation in southern Africa creates a public demand for severe weather information systems for convective cells. Such a system was set up in GRASS GIS, using rule‐based expert systems to classify convective clouds. It isolates storm cells from stacks of reflectivity fields and derives information about their development stages. This data is both archived and also used to send out customised messages to target groups in specific areas of interest. Further, nationwide HTML‐maps can be created, serving as an interactive front‐end for a web‐based weather information system. This service can also be made accessible from remote locations by broad‐casting it as a datastream from satellite through the Worldspace digital radio system.     

A Review of Sampling Effects and Response Bias in Internet Participatory Mapping (PPGIS/PGIS/VGI)

Global interest in participatory mapping described as public participation GIS (PPGIS), participatory GIS (PGIS), and volunteered geographic information (VGI) continues to grow, but systematic study of spatial data quality and sampling effects is limited. This article provides a review and meta‐analysis of Internet‐based PPGIS studies conducted during the period 2006–2015 (n=26) to answer the following research questions: (1) How does mapping effort, as a proxy measure for spatial data quality, differ by sampling group? (2) Does the purpose and context of PPGIS influence mapping results? (3) What is the potential for mapping bias through sampling design? (4) Given the results, what should be the focus of future PPGIS research? Mapping effort was highest in sampling groups whose livelihoods were closely related to the purpose of the study, there was greater mapping effort in household sampling groups compared to volunteer groups, and participant domicile had strong effects on mapped results through spatial discounting. The use of online Internet panels provides higher response rates but lower spatial data quality. Future research should focus on increasing sampling response rates, assessing social trade‐offs using alternative spatial weighting schemes, and examining the capacity of the public to select land use alternatives as a complement to traditional expert‐driven planning systems.     

无源微波遥感技术在海冰测厚中的应用研究

　In recent years, microwave radiometry has been developed as a powerful technique for remote Sensing of Sea ice in China. Since 1986 the thermal emission from sea ice in Liaodong Bay and Bohai Bay has been measured by multi-frequency microwave radiometers designed by Changchun Institute of Geography, Academia Sinica.     

一种使用卫星反射信号探测海冰分布新方法

利用TechDemoSat-1低轨道卫星采集的卫星反射信号生成的时延多普勒图（delay-doppler map,DDM）探测北极格陵兰岛（Greenland）地区的海冰分布。由于卫星散射信号在海冰和海水上分别遵循相干散射和漫散射模型,与海水相比,海冰的时延多普勒图扩散较少,所以从海水到海冰的过渡会导致时延多普勒图中高于一定能量值的像素数量减小。提出了一种基于相邻DDM像素数量比值的检测方法,通过采用一定阈值来区分海冰和海水的时延多普勒图,用于分析格陵兰岛地区海冰的分布情况。还利用多期数据分析了格陵兰岛地区海冰分布随时间的变化。通过与美国国家冰雪数据中心提供的数据比对,利用数学统计方法对本文提出的方法性能进行了评估。结果显示,该方法的判断成功率可以达到98.76%~99.21%,整体评估成功率约为99.09%。     

The Development of the Chagas' Online Data Entry System (CODES-GIS)

This article describes a web‐based data entry and GIS‐driven mapping system designed for an ethnographic and entomological survey of Chagas’ disease, an emerging zoonotic disease, and Triatoma dimidiata, a primary vector, in the Los Tuxtlas region of Veracruz, Mexico. To better understand this disease in the region, a collaborative, multi‐disciplinary study was initiated to conduct a spatial investigation of T. dimidiata and a community‐by‐community survey of local perceptions of the disease. In order to facilitate such a collaborative effort the CODES‐GIS was developed. This system allows for (near) real‐time mapping, analyses, disease reporting, and results sharing. CODES‐GIS provides a framework for a research team working in a remote area with limited technology, software, or GIS expertise to benefit from (near) real‐time spatial analyses performed at collaborating institutions. The system is bi‐directional, where field personnel can upload data to the system for field‐based map production. Likewise, laboratory personnel can upload diagnostics data for viewing by field personnel. In this way, the system provides a virtual link between the field and the laboratory to increase the speed at which results are returned to the local community. The CODES‐GIS is described along with a selection of study results.     

Building Web-Based Spatial Information Solutions around Open Specifications and Open Source Software

Geographic Information Systems (GIS) are moving from isolated, standalone, monolithic, proprietary systems working in a client‐server architecture to smaller web‐based applications and components offering specific geo‐processing functionality and transparently exchanging data among them. Interoperability is at the core of this new web services model. Compliance with Open Specifications (OS) enables interoperability. Web‐GIS software's high costs, complexity and special requirements have prevented many organizations from deploying their data and geo‐processing capabilities over the World Wide Web. There are no‐cost Open Source Software (OSS) alternatives to proprietary software for operating systems, web servers, and Relational Database Management Systems. We tested the potential of the combined use of OS and OSS to create web‐based spatial information solutions. We present in detail the steps taken in creating a prototype system to support land use planning in Mexico with web‐based geo‐processing capabilities currently not present in commercial web‐GIS products. We show that the process is straightforward and accessible to a broad audience of geographic information scientists and developers. We conclude that OS and OSS allow the development of web‐based spatial information solutions that are low‐cost, simple to implement, compatible with existing information technology infrastructure, and have the potential of interoperating with other systems and applications in the future.     

基于GIS服务链的遥感影像分布式融合处理

提出了基于Web服务技术、OGC规范和工作流技术,以实现与平台无关的、具备流程编排能力的地理空间处理服务链框架,用于支持复杂的在线空间处理任务.在该框架基础上实现了一个在线遥感影像融合处理示例.该示例展示了利用OGC WCS、WPS,WSDL,UDDI和BPEL4WS等成熟的标准规范来构建GIS服务链,使得客户应用程序...     

Producing an Indigenous Knowledge Web GIS for Arctic Alaska Communities: Challenges,Successes, and Lessons Learned

A traditional knowledge “Iñupiaq Web GIS”, based on a five‐year study and containing observations and environmental knowledge of Iñupiat communities indigenous to Arctic Alaska, was incorporated into a Web‐based platform. The website, “Arctic Cultural Cartography,” was created to be an open portal through which the password‐protected “Iñupiaq Web GIS” could be accessed. We discuss the process of developing the web GIS including the incorporation of user‐friendly features such as links to interactive maps, video clips of interviews, discussion boards, and the integration of popular web interfaces such as Facebook. We also discuss short‐ and long‐term goals for the further development of the GIS, its potential as a sustainable, participatory online database for sharing pertinent ecological knowledge, and challenges in achieving optimal community involvement given constraints imposed by remote locations with limited bandwidth.     

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.     

基于GNSS-R的后续海冰观测实验

冬季海上浮冰的活动给海上生产和海上运输带来了严重的负面影响,需要对海冰进行全天候、大范围检测。此次实验根据海水与海冰电磁特性的差异,利用较为经济的导航卫星反射信号遥感方法,在天津渤海岸展开连续的观测和数据采集。对同一颗GPS卫星的不同极化类型的反射信号从能量的角度分析海冰分布情况,在误差最小的情况下得出分析结果：不同极化类型的导航卫星反射信号均可从不同角度表征海冰覆盖信息。     

基于CryoSat-2数据的海冰厚度估算算法比较

以北极为研究区,使用CryoSat-2数据,利用现有海冰厚度卫星测高研究中4种主流算法(Laxon03算法、Kurtz09算法、Yi11算法和Laxon13算法)分别对北冰洋海冰厚度进行估算,并将估算结果与研究区IceBridge机载激光测高冰厚数据进行了比较,探索各算法海冰厚度估算的差异,寻找最优的估算算法,为估算长时序海冰厚度提供基础和参考。结果表明,4种算法估算的海冰厚度空间分布较为一致,但不同算法估算的结果差异较大,可达0.476 m;4种算法估算结果大小依次为Laxon03算法、Yi11算法、Laxon13算法、Kurtz09算法;4种算法估算的平均海冰厚度差异,在北极波弗特海海域最大,其次是北极中心海域、格陵兰和挪威海;Laxon13算法估算结果相对于IceBridge观测结果与其他算法相比,具有最小的平均偏差和均方根误差,是卫星测高估算海冰厚度的最优算法。     

Web GIS组件方法研究

在分析WebGIS二次开发需求的基础上，提出了基于JavaBean的WebGIS组件概念，并详细阐述其特征、体系结构和空间数据组织，结合实例Internet GIS-GeoSurfV4.0介绍了系统的设计与实现以及二次开发的方法与比较。     

利用目标分解特征的全极化SAR海冰分类

特征提取及其选择是SAR海冰分类的重要步骤之一。在众多特征中选取有效特征,进而构建表达地物类型的特征空间是提高分类精度的关键。为此,本文提出一种基于目标分解特征的全极化SAR海冰分类算法。首先,对全极化SAR数据进行多视化处理及滤波操作,生成相干矩阵;其次,对相干矩阵进行目标分解,并针对分解结果提取散射特征参数,进而构建特征空间;再次,通过对所提取的特征进行统计相关性分析,并对高相关特征采用PCA降维,以优化特征组合;最后,设计BP神经网络分类器,并将所得的优化特征矢量作为输入,海冰类别为输出,实现海冰分类。本文以格陵兰中部海域作为研究试验区域,采用L波段ALOS PALSAR全极化数据。通过对本文算法与对比算法的分类结果进行定性定量分析,可以得出本文所选取的特征对海冰识别较好。此外,通过对利用各个不同特征海冰分类结果的性能分析,可以得出基于散射模型的目标分解比基于特征值的H/α/A分解更有助于海冰分类。     

网络地理信息系统实现技术与发展研究

网络地理信息系统是网络与地理信息系统这两项技术的集成。本文简要地分析了WebGIS的基本特征和产生的重大作用。作为“数字地球”和“数字区域”建设的关键性技术，文中分析了几种实现方法并对其发展做了一些研究。     

Defining a Sea Ice Flag for Envisat Altimetry Mission

This letter presents the development of a sea ice flag algorithm for the Envisat altimetry mission to detect sea ice corrupted sea surface height data within quality control processing. The algorithm takes advantage of having both passive and active microwave sensors on the same platform with coregistered measurements. Its performances have been evaluated based on collocations between the along-track Envisat data with reference maps built from combination of daily grids of sea ice concentration from SSM/I sensors and backscatter cross section from SeaWinds scatterometer on QuikSCAT satellite.     

基于多特征的Gaofen-1海冰影像监督分割

冬季沿海地区的海冰检测工作对该地区居民的生产生活具有重要的指导意义,同时可以根据海冰变化检测气候变暖情况。海冰影像分割是海冰检测的基础。在众多海冰影像数据源中,Gaofen-1海冰影像因其丰富的光谱特征、较高的空间分辨率、简单的数据结构,在变化监测中具有重要应用价值。本文提出了一种基于红绿蓝3个光谱通道的灰度共生矩阵,提取遥感影像的纹理特征和光谱特征构成多特征的Gaofen-1海冰影像监督分割方法。以Gaofen-1合成的模拟海冰影像和某海湾地区真实Gaofen-1海冰影像进行分割实验,实验结果很好地证明了算法的可行性和可靠性。