Volunteered Geographic Information: A Bicycling Enthusiast Perspective

Mapping technologies have made considerable strides in recent decades. Global positioning systems (GPS), remote sensing satellites, Web-based mapping services, and geographic information systems (GIS) have facilitated the collection, distribution, analysis, and ultimately interaction with geospatial information. In particular, portable GPS have altered how individuals participate in mapping. Individuals can use GPS to collect tracings of their personal interactions with the environment. These interactions can then be uploaded to one of many available Web-based mapping services. Once uploaded, the geospatial data can be mapped and shared among the broader community of users. Such volunteered geographic information (VGI) exemplifies the conceptualization of an individual collecting, mapping, and sharing personal geographic information. This paper focuses on challenges surrounding VGI. To help place these challenges in a broader context, specialized Web services and GPS technologies developed for the bicycling community will serve as examples of the current status and future prospects of VGI.     

浅论自发地理信息的数据管理

自发地理信息（volunteered geographic information,VGI）由大众志愿者自发标报,导致其可信度具有诸多不确定性,但目前的研究工作很少考虑用户信誉对于VGI质量的影响,因此提出基于用户信誉的VGI可信度计算模型。首先提出了VGI的用户信誉模型,模型综合考虑了用户的初始信誉和评价信誉两方面,在此基础上综合地理要素的编辑过程和贡献者的信誉等因素发展了地理对象的可信度计算模型。最后采用OpenStreetMap的真实历史数据中的线对象进行实验,实验结果表明,线要素的质量和可信度值呈正相关关系。本文从可信度的角度来评价自发地理信息,为VGI的质量评价和筛选提供了新的视角。     

浅论自发地理信息的数据管理

分析了自发地理信息(volunteered geographic information,VGI)数据的来源、分类、特点与管理要求,探讨了VGI数据清理与质量控制,研究了以高效处理绘图查询与数据更新为目标的VGI图形数据管理问题,提出了动态线综合二叉树与缩放四叉树的设计思想,以解决VGI图形数据管理中的难点问题。     

志愿者地理信息研究与应用初探

随着计算机技术与互联网技术、卫星定位技术、移动终端技术的发展,地理信息服务的模式正在发生改变,志愿者地理信息时代悄然而来。文章以志愿者地理信息的产生为索引．从数据的采集、处理、管理和质最控制等方面就国内外志愿者地理信息的研究与应用情况进行了回顾,讨论了目前志愿者地理信息存在的问题与发展趋势。     

志愿者地理信息中天桥的自动识别方法

基于天桥的几何与属性特征,提出了一种志愿者地理信息中自动识别天桥的方法。天桥从几何结构上可分为主桥和附属设施两个部分,主桥部分特征鲜明,可以视为两类分类问题,依据其几何特征和属性特征构建特征空间,利用支持向量机的方法进行识别;附属设施部分可依据已识别的天桥主桥,按照路段的长度、属性等判定规则进行识别,从而完成整个天桥的自动识别。以北京市OpenStreetMap(osm)数据进行试验验证的结果表明,本文提出的方法能有效地识别出志愿者地理信息中的典型天桥结构,可以为志愿者地理信息道路网的多尺度建模与化简、步行导航等提供帮助。     

自发地理信息兴趣点数据在线综合与多尺度可视化方法

移动及Web环境下,集成各种自发地理信息POI数据与地理框架背景数据的混搭式地图应用,越来越多地出现在主流地理信息平台及LBS服务中。由于缺乏适宜的在线多尺度可视化机制,这种POI数据表达上通常出现拥挤、压盖等冲突现象。针对该问题,本研究将传统的尺度变换方法与在线环境相结合,提出一种面向城市设施POI数据的多尺度可视化策略。即由服务器端通过预处理方式对POI数据进行多层次结构化组织;在此基础上,客户端依据显示比例尺导出对应层次的POI目标,并通过移位操作解决局部存在的符号表达冲突现象。试验表明,该方法符合数字化网络应用的在线实时需求,同时也能获得较高质量的多尺度表达效果。     

一种基于参考数据的志愿者地理信息质量评价方法

志愿者地理信息数据大都依靠志愿者上传,数据质量未知,阻碍了志愿者地理信息的广泛应用,因此是志愿者地理信息首要解决的问题。本文分析了影响志愿者地理信息质量的相关因素和基于参考数据评价方法的相关研究成果,在此基础上提出了一种基于参考数据的志愿者地理信息质量评价方法,以最常见的数据完整性和数据精度作为质量评价的质量元素,详细论述了这两种质量元素的内涵。针对数据完整性评价,提出了与匹配相结合的几何数据完整性度量方法和基于属性项饱和度的属性数据完整性度量方法;针对几何数据精度评价,提出了基于变缓冲区的度量方法。然后给出了该评价方法的一般流程。最后,以深圳市Open Street Map数据为例,选取最新导航数据作为参考数据进行试验验证。实验结果表明,深圳市Open Street Map数据点要素完整性较差,但是线要素完整性与精度都非常高,可以作为基础地理信息的更新数据源。     

Dynamic GIS Case Studies: Wildfire Evacuation and Volunteered Geographic Information

Incorporating the temporal element into traditional GIS is a challenge that has been researched for many years and has many proposed solutions. The implemented system "Extended Dynamic GIS" or EDGIS is based on the "geo-atom" and Space Time Point (STP). EDGIS provides a platform for spatiotemporal data representation, storage, and query in order to address the need for a dynamic GIS to manage complex geographic data types. The system has the capability of executing spatiotemporal object interaction queries (OIQs) such as crossing and coincidence of field-objects and object-fields. In this article existing dynamic GIS analysis techniques are further improved and enhanced through exploration of more in-depth case studies. Further examined here are applications to wildfire evacuation modeling and travel scenarios of urban environments with individuals providing volunteered geographic information (VGI). The EDGIS platform provides a means for interacting with a range of dynamic geographic phenomena. The areas of transportation, location based services (LBS), hazards, and geo-sensor networks provide challenges intertwined with the above applications as well as additional challenges pertinent to the ongoing GIScience research topic of spatiotemporal GIS. Using EDGIS to explore the described case studies of wildfire evacuation as well as VGI provides the advancements described above and demonstrates implemented uses for dynamic GIS.     

Accurate Attribute Mapping from Volunteered Geographic Information: Issues of Volunteer Quantity and Quality

Crowdsourcing is a popular means of acquiring data, but the use of such data is limited by concerns with its quality. This is evident within cartography and geographical sciences more generally, with the quality of volunteered geographic information (VGI) recognized as a major challenge to address if the full potential of citizen sensing in mapping applications is to be realized. Here, a means to characterize the quality of volunteers, based only on the data they contribute, was used to explore issues connected with the quantity and quality of volunteers for attribute mapping. The focus was on data in the form of annotations or class labels provided by volunteers who visually interpreted an attribute, land cover, from a series of satellite sensor images. A latent class model was found to be able to provide accurate characterisations of the quality of volunteers in terms of the accuracy of their labelling, irrespective of the number of cases that they labelled. The accuracy with which a volunteer could be characterized tended to increase with the number of volunteers contributing but was typically good at all but small numbers of volunteers. Moreover, the ability to characterize volunteers in terms of the quality of their labelling could be used constructively. For example, volunteers could be ranked in terms of quality which could then be used to select a sub-set as input to a subsequent mapping task. This was particularly important as an identified subset of volunteers could undertake a task more accurately than when part of a larger group of volunteers. The results highlight that both the quantity and quality of volunteers need consideration and that the use of VGI may be enhanced through information on the quality of the volunteers derived entirely from the data provided without any additional information.     

Measuring the Reliability of Wheelchair User Route Planning based on Volunteered Geographic Information

The development of a wheelchair user friendly route planning application inherits a number of special requirements and details that need to be considered during the generation of the routing graph and the corresponding algorithm, making this task much more complex than car or pedestrian related applications. Each wheelchair type and, more importantly, each individual user might have different needs with regards to the way condition or other criteria. This study proposes a new approach to route planning for wheelchair users tailored for individual and personal requirements provided by the user and the calculation of a reliability factor of the computed wheelchair path. The routing graph is based on the freely available Volunteered Geographic Information (VGI) retrieved from the OpenStreetMap (OSM) project. The newly created algorithm is evaluated and tested for a selected area in Bonn, Germany. A new reliability factor is introduced that gives direct feedback about the quality of the generated path. Similar factor estimations can also be utilized for multiple route planning applications where VGI or other commercial or administrative data is implemented and more detailed factors than a simple geometric representation of a street network are of importance.     

地理信息在线服务方式的发展

概述了地理信息在线服务的必要性,是实现从模拟地图或电子光盘的拷贝服务到系统服务的转变,是从数据提供到增值服务的转变。阐述了地理信息在线服务的主要方式,包括地理信息发布、地理信息分发、地理信息在线应用和地理信息一站式访问等。介绍了地理信息在线服务在公共地图网站、国外地理信息公共平台和国内数字城市建设领域的应用情况。     

Trust as a proxy indicator for intrinsic quality of Volunteered Geographic Information in biodiversity monitoring programs

In this article, we present a fuzzy model for intrinsic quality assessment of Volunteered Geographic Information (VGI) on species occurrences obtained by Citizen Science (CS) biodiversity monitoring programs. The proposed VGI quality assurance approach evaluates the thematic and positional quality of the crowdsourced biodiversity observation in terms of the trustworthiness of the observation by combining three indicators of consistency with habitat, consistency with surroundings, and reputation of contributor, that characterize the geographical and social aspects of trust in VGI. To evaluate the performance and usability of the proposed approach for evaluating the trustworthiness of crowdsourced observations and detecting thematic and positional errors in crowdsourced observations, the developed approach was applied to the crowdsourced observations on Acer macrophyllum collected through the CS biodiversity monitoring projects of E-Flora BC and iNaturalist. The result of a conformity test at the optimal acceptance threshold (sensitivity = 0.99, specificity = 0.8, and Cohen’s kappa = 0.79), the achieved area under the curve (AUC) value (AUC = 0.98), and the results of the complementary investigation on the predictions of the proposed model indicated that the proposed fuzzy trust model exhibited promising predictive performance and was able to flag the majority of attribute and positional errors in the crowdsourced biodiversity observations.     

结合VGI数据与资源三号遥感影像的路网整体构建

正地理空间数据是地理信息系统的血液,是数字地球、智慧地球、智慧城市建设的基础。地理信息的快速变化及数据采集方式的多样化使得多源数据的整合与集成技术成为地理信息科学发展的关键问题之一。特别是随着Web2.0和传感器技术的快速发展,为普通大众参与地理空间数据的生产与维护提供了必要的软、硬件支持。在     

Assessing the Accuracy of Volunteered Geographic Information arising from Multiple Contributors to an Internet Based Collaborative Project

The recent rise of neogeography and citizen sensing has increased the opportunities for the use of crowdsourcing as a means to acquire data to support geographical research. The value of the resulting volunteered geographic information is, however, often limited by concerns associated with its quality and the degree to which the contributing data sources may be trusted. Here, information on the quality of sources of volunteered geographic information was derived using a latent class analysis. The volunteered information was on land cover interpreted visually from satellite sensor images and the main focus was on the labeling of 299 sites by seven of the 65 volunteers who contributed to an Internet‐based collaborative project. Using the information on land cover acquired by the multiple volunteers it was shown that the relative, but not absolute, quality of the data from different volunteers could be characterized accurately. Additionally, class‐specific variations in the quality of the information provided by a single volunteer could be characterized by the analysis. The latent class analysis, therefore, was able to provide information on the quality of information provided on an inter‐ and intra‐volunteer basis.     

土木工程专业地理信息系统课程教学研究

在介绍GIS在土木工程应用的基础上,结合现代土木工程特点,分析了在土木工程人才培养中开设GIS课程的必要性,探讨了其教学内容。针对土木工程专业学生知识面的特点研究了GIS理论教学的方法,提出综合应用各种教学方法和现代教育技术,以改善教学效果。阐述了GIS实验教学的重要性,结合应用型GIS教学方法,提出了不同层次的实验项目和提高学生应用能力的途径。论述了以突出应用能力培养和平时学习效果为目的的考核方法,研究了针对土木专业GIS教学质量保障的有效途径。     

基于DEA模型的GIS工程技术开发方法的综合评价

引入数据包络分析 (DEA)评价方法对GIS进行综合评价,评价结果一方面可以对工程建设进行有效的设计与组织,另一方面可以通过建立合理的评价指标体系来优化工程项目。对国土资源和房屋管理系统的设计开发进行了分析评价,并给出了实例性结论。     

地图制图学与地理信息工程学科发展趋势

在简要分析地图学发展演变轨迹的基础上,针对目前地图制图学与地理信息工程领域存在的问题及国家和军队信息化建设日益增长的需求,提出地图制图学与地理信息工程学科研究的六大热点问题,即异构地理空间数据同化、由着重地理信息获取一端向面向用户的地理信息深加工一端漂移、地理信息服务的网络?网格化、空间数据综合的智能化、地理信息系统(GIS)与虚拟地理环境(VGE)的集成与一体化、以多模式(Map、GIS、VGE)时空综合认知模型为核心的地图制图学与地理信息工程学科理论体系等,并分别论述开展6个热点问题研究的必要性、现有基础和主要研究内容。     

地理信息系统在消防工程中的应用

在介绍地理信息系统（GIS）基本功能的基础上,阐述了GIS在消防工程中（包括城市消防站的选垃、城市消防调度指挥、消防管理等方面）的应用,指出应用中存在和需要解决的一些问题,最后展望GIS在消防工程中的发展趋势。     

A Perspective on the Fundamentals of Fuzzy Sets and their Use in Geographic Information Systems

The development of fuzzy sets in geographic information systems (GIS) arose out of the need to handle uncertainty and the ability of soft computing technology to support fuzzy information processing. An overview of the fundamentals of fuzzy sets is used to illustrate its use in GIS. The use of some terms within both the GIS and fuzzy information processing community is clarified. Since one of the key problems when applying fuzzy sets to GIS problems is in the specification of grades of membership, the many methods used to specify memberships in fuzzy sets in GIS applications are presented. The α–cut is defined and shown to be of increasing importance in GIS. Non–compensatory and compensatory connectives are compared. Aggregation operators are reviewed and shown to be useful in a number of GIS studies. Fuzzy relations and fuzzy control systems are briefly discussed with reference to their use in GIS and in relation to the development of modern soft computing technology. Several features of fuzzy sets make that paradigm attractive for use in GIS. It is concluded that as GIS–related applications increase in their levels of complexity and sophistication fuzzy sets will play a major, cost effective role in their development.     

地理信息快速更新需求下的在线调绘系统设计探讨

随着我国基础地理信息数据库建设的快速发展,已由初始建库、经历全面更新、进入动态更新,传统外业调绘的作业模式与技术方法已难以满足地理信息快速更新的应用需求。本文结合GIS,GPS,3G等技术,集成地理信息采集、无线数据传输、数据保密处理等功能,设计了集中式管理与分布式作业相结合的在线调绘作业模式和技术系统,为地理信息的快速更新提供了一种新的技术思路。