基于EMD的空间信息剖分一体化编目模型研究

针对目前空间信息编目多样、缺乏全球统一编目体系的现状,借鉴地理空间信息分类框架,结合地图分幅拓展球面剖分理论,提出了基于EMD的空间信息剖分一体化编目模型.在此基础上,设计了统一剖分编目中间件,搭建了全球空间信息统一剖分编目数据的管理框架.基于EMD的空间信息剖分一体化编目模型为实现空间数据的全球化、层次化和规范化管理奠定了理论基础.     

多级地理空间网格框架及其关键技术初探

为了有效管理、组织和利用海量空间数据,解决存储架构与现有空间数据结构不一致的矛盾,在融合国内外各种球面剖分模型优点基础上,设计了一种多级地理空间网格框架。该网格框架以地图分幅划分方式为基础,利用经纬度间隔对全球进行层次性剖分,形成遥感数据、测绘数据及其他空间数据的统一组织框架。通过对网格单元的地址与属性编码,实现空间数据的直接存储和索引,从而完成对空间信息的无缝拼接与多尺度管理。最后阐述了实现地理空间网格框架的关键技术,包括空时一体化技术、计算集群存储技术和空间索引技术等。     

基于全球剖分模型的分发数据预处理与制备方法

随着对地观测技术的迅猛发展,人类获取的空间影像数据更加丰富,如何利用有限的网络带宽响应空间影像数据的实时请求并进行分发是目前空间信息服务的重要研究内容。该文采用地球剖分的思想设计与实现了一种全球空间数据分发系统的影像数据预处理与制备方法。该方法根据GeoSOT剖分方案对地球空间进行多级、多尺度划分,建立剖分编码与单幅影像内数据块的多尺度逻辑索引,这种索引有利于以剖分索引面片为单位进行多尺度数据块的提取与分发。     

全球空间数据剖分模型分析

随着数字地球发展,全球空间信息多尺度表达和管理使得传统平面格网系统的局限性越来越明显,建立全球数据多尺度剖分模型已成为国内外学者关注的热点。该文介绍并分析全球剖分系统,根据剖分单元的形状和最终投影曲面的性质对球面剖分系统进行分类。总结出球面剖分系统具有连续性、稳定性、层次性和近似均匀性等优点,既有效避免了传统平面格网表达全球数据时存在的数据冗余问题,又克服了不规则球面剖分系统无法进行层次关联的缺陷,在管理全球、多层次和海量的空间数据时具有优势。     

基于GeoSOT的遥感影像云索引模型研究

针对目前遥感影像中云信息描述简单、云的空间分布信息不足而限制影像局部云信息检索的现状,提出了基于GeoSOT的影像云索引模型。该模型根据空间信息建立GeoSOT网格与遥感影像的对应,通过判断每个GeoSOT剖分面片对应的影像数据块是否有云,并记录剖分面片编码和判断结果,实现对遥感影像中局部云信息建立索引;在检索影像中局域云信息时,根据剖分面片编码查找云信息标识即可。同时,探讨了不同等级影像数据产品采用精确逻辑剖分和冗余逻辑剖分构建影像云索引的方法,设计了影像云索引的数据结构,分析了影像数据建立云索引的存储代价。通过仿真实验表明,对遥感影像构建基于GeoSOT剖分编码的云索引代价小,其存储量约为原数据的0.01%,提高了影像中局部云信息查询效率,为计算机自动选取高质量的影像提供了一个有效的技术途径。     

基于EMD的遥感影像数据组织模型

针对目前遥感数据组织以时间为基准、同一区域不同部门遥感数据标识不统一的现状,鉴于全球剖分网格具有多层次、全球覆盖、网格单元编码全球唯一性和对传统地图图幅的继承性等特点,介绍了基于地图分幅拓展的全球剖分模型EMD,提出以EMD剖分面片为单元、采用剖分面片编码标识并管理遥感数据及其相关资源的数据组织框架.试验分析表明,基于EMD的遥感影像数据组织可行,且基于剖分面片编码的数据检索具有较高效率.     

遥感影像剖分金字塔研究

分析了全球剖分格网与影像金字塔的优点与不足,结合两者的优势提出了剖分影像金字塔模型及建塔策略,利用全球剖分格网面片编码的唯一性和Hilbert曲线空间连续性对影像块进行索引与组织。针对基于影像块组织的特点,提出了剖分影像金字塔局部更新的方案。实验结果表明,剖分影像金字塔不仅具有传统影像金字塔在快速浏览上的优势,并且由于其编码和索引的优势,使得在局部影像提取和更新方面效率更高,有一定的使用价值。     

面向地理对象多尺度表达的剖分编码方法研究

现有模型对影像数据中的地理对象进行多尺度表达很困难,鉴于全球剖分模型在对地理对象表达时所具备的全球唯一性、层次性、多尺度性、编码具有地学含义等特点,提出了面向地理对象多尺度表达的剖分编码方法,目的是对地理对象赋予统一的剖分编码,使编码具有地学含义和多尺度特性.实验证明,面向地理对象多尺度表达的剖分编码方法可以满足地理对象多尺度剖分化表达的需要,为新一代GIS解决地理信息"尺度鸿沟"问题,向用户提供"连续"、"自适应"的表达尺度奠定了基础.     

GTP模型中四面体的引入及其空间模型扩展

该文从空间拓扑概念出发,分析了基于广义三棱柱(GTP)模型建立空间实体间拓扑关系时的不足。针对GTP进行平面剖切时存在的缺陷,讨论了在GTP模型中加入新的几何元素——四面体作为辅助元素的必要性,并将空间实体的描述分为几何元素和实体元素两类。在此基础上,对原有GTP模型进行了改进,建立了几何元素和实体元素之间的拓扑关系。并有效地解决了空间实体的3D平面剖切问题。     

球体退化八又树网格编码与解码研究

球面离散网格只进行地球表面剖分,而球体退化八叉树网格（SDOG）可对整个球体空间进行多层次连续的三维递归剖分,且网格大小均匀、变形稳定,适合作为全球三维空间基础框架。该文研究SDOG的编码与解码问题,剖析了SDOG网格编码的原理,提出两种网格编码方法,即单层次退化Z曲线填充编码（SDZ）和多层次退化z曲线填充编码（MDZ）,设计了相应的编码与解码算法。通过实验比较了SDZ、MDZ和QuaPA主码在编码效率、解码效率及编码长度方面的差异,结果表明MDZ是一种优异的多分辨率动态网格编码方法,可服务于基于SDOG的全球三维空间基础框架。     

Enabling smart data selection based on data completeness measures: a quality-aware approach

Geographic information system (GIS) users rely heavily on the versatile operations of GIS software and the abundant variety of geospatial data from different resources to satisfy their application requirements. However, the convenient use of GIS software has resulted in users easily ignoring the threat of data misuse because of the lack of understanding of data quality. Here we argue that data quality considerations must be coherently assimilated into the GIS operation design to visually present helpful information and ensure the accuracy of data for decision making. Data completeness is selected in this paper to demonstrate how the use of data quality information opens a new dimension to the design of future GIS software. We propose a new model for the representation, analysis, and visualization of data completeness information. With the brand new quantitative measures and informative visual approach, understanding of the data completeness of the illustrated contents in the map interface is enhanced, and inappropriate dataset selection can be effectively prevented. Thus, this paper presents an innovative, integrated and geospatial concept of future GIS operation design, where users are constantly aware of the continuously changing status of data quality based on formalized and quantitative data quality theories.     

Use of Geospatial Data and Technology for Wilderness Search and Rescue by Nonprofit Organizations

Geospatial data and tools are key in locating lost or missing persons in as short a time as possible. In this study, we used a geographic information system (GIS) to analyze four years of search and rescue (SAR) mission data from Colorado to determine the appropriate use of GIS for volunteer-based SAR organizations with limited resources and GIS expertise. GIS can provide more sophisticated analyses of geospatial data than simple mapping technologies, but our findings indicated that complex spatial analysis might not be required on all missions, because the majority of missions were completed within six to ten hours. Instead, new technologies such as tablets with mapping software and online GIS systems that provide quick and easy access to up-to-date geospatial data such as imagery offer capabilities that could improve mission planning. Here we provide a framework in which SAR missions can apply geospatial technologies to aid with missions, identify critical “hotspots,” and enhance postanalysis and training. The work here is highly applicable for nonprofit SAR groups when deciding on what GIS technologies to consider for their areas.     

地理视频数据模型及其应用开发研究

讨论地理视频的基本概念和数据模型,尝试提出地理视频数据的实体-关系图,并在网络环境中进行地理视频应用开发.地理视频数据模型的核心要素是:对视频帧进行位置和语义描述,建立视频片段的轨迹图层和元数据,并在轨迹图层中扩充视频帧线性参照.通过空间参照、线性参照和语义参照将视频数据与地理数据集成,实现地理视频的查询、检索、播放和地图跟踪.以河南大学校园和开封市公路网络为例,采集地理视频数据,建立地理视频数据库,发布网络地图和视频服务,并分别采用最新的Adobe Flex框架、ArcGIS Server ADF和JavaScript Mashup方式,开发网络视频GIS应用系统.原型系统开发表明,地理视频数据模型适用于网络视频GIS开发,且在技术实现上较为简单.     

Usability evaluation for geographic information systems: a systematic literature review

The growing dissemination of geographic information systems (GIS) in recent years has increased the availability and use of geospatial tools. Despite this trend in GIS, usability is often not considered, and studies on usability are relatively rare. However, it has been shown that the effectiveness, efficiency and user satisfaction of these tools when used for geospatial tasks may be impacted by their design and terminology. In this article, we present a comprehensive review of the relevant literature. We analyze and compare publications of GIS usability evaluations, the methods that were used, and the findings reported. We thus produce a more detailed picture of GIS usability evaluations. Our contributions are (1) an overview of methods applied in case studies for evaluating the usability of GIS; (2) the identification of gaps and resulting weaknesses of previous studies; and (3) challenges and opportunities for future GIS usability studies. Our findings reveal a lack of usability guidelines for GIS, a lack of methods for analyzing complex workflows, and a lack of usage studies over longer periods of time. These contributions can help GIS developers and designers to improve the usability of their systems.     

Web-based geospatial multiple criteria decision analysis using open software and standards

The emerging ubiquity of geospatial information is providing an unprecedented opportunity to apply Geographical Information Systems (GIS)-based multiple criteria decision analysis (MCDA) to a broad spectrum of use cases. Volunteered geographic information, open GIS software, geoservice-based tools, cloud-based virtualized platforms, and worldwide collaboration of both domain experts and general users have greatly increased the quantity and accessibility of geospatially referenced data resources. Currently, there is a lack of GIS-based MCDA tools that integrate this decision-driven process within a widely accessible, robust geoframework environment, designed for user-friendly interaction. In this contribution, we present a conceptual workflow and proof-of-concept software application, Geocentric Environment for Analysis and Reasoning (GEAR), which provides a viable transition path to enhance geospatial MCDA in the age of open GIS. We propose a Web-based platform that leverages open-source geotechnologies to incorporate a wide variety of geospatial data formats in a common solution space to allow for spatially enhanced and time-relevant decision analysis. Through the proposed workflow, a user can ingest and modify heterogeneous data formats, exploit temporally tagged data sources, create multicriteria decision analysis models, and visualize the results in an iterative and collaborative workspace. A sample case study applied to disaster relief is used to demonstrate the prototype and workflow. This proof-of-concept Web-based application provides a notional pathway of how to connect open-source data to open-source analysis through a geospatially enabled MCDA workflow that could be virtually accessible to many levels of decision makers from individuals to entire organizations.     

Using open‐ended geographic information system assessments to allow students to construct relevant geographies given the internationalisation of tertiary education in New Zealand

The geospatial skills shortage in New Zealand requires the development of more undergraduate geographic information system (GIS) courses. However, the internationalisation of New Zealand's tertiary education system has resulted in an increasingly diverse tertiary student population, which makes it challenging to teach GIS in a way that maximises relevance to all tertiary students. One approach to this challenge is to make use of the recent proliferation of openly available GIS data, and to internationalise GIS curricula by using open‐ended assessments that provide students with the opportunity to learn GIS by constructing their own geographies of relevance.     

Building the distributed geographic SQL workflow in the Grid environment

Over recent years, massive geospatial information has been produced at a prodigious rate, and is usually geographically distributed across the Internet. Grid computing, as a recent development in the landscape of distributed computing, is deemed as a good solution for distributed geospatial data management and manipulation. Thus, the Grid computing technology can be applied to integrate various distributed resources into a ‘super-computer’ that enables efficient distributed geospatial query processing. In order to realize this vision, an effective mechanism for building the distributed geospatial query workflow in the Grid environment needs to be elaborately designed. The workflow-building technology aims to automatically transform the global geospatial query into an equivalent distributed query process in the Grid. In response to this goal, detailed steps and algorithms for building the distributed geospatial query workflow in the Grid environment are discussed in this article. Moreover, we develop corresponding software tools that enable Grid-based geospatial queries to be run against multiple data resources. Experimental results demonstrate that the proposed methodology is feasible and correct.     

对地理信息分类编码的认识与思考

面向GIS的地理信息分类编码是在概念水平上解决空间信息分层组织与属性数据库结构设计的重要方法。该文从地理实体、地理数据与地理信息概念角度 ,探讨地理信息分类编码对象的本质特征 ;简要分析大多数商品化GIS软件中属性数据的表达方式 ,指出地理信息分类编码实质上是从GIS数据组织的概念层次上对属性信息的分类分级 ;提出地理信息分类粒度概念 ,并建立地理信息分类模型 ,列举了在不同视图下的粗粒地理信息分类方案和代码用途 ;提出并讨论地理信息分类编码尚待进一步研究的问题 ,以及国内长期以来难以形成地理信息分类标准的原因。