Quality assessment of OpenStreetMap data using trajectory mining

OpenStreetMap (OSM) data are widely used but their reliability is still variable. Many contributors to OSM have not been trained in geography or surveying and consequently their contributions, including geometry and attribute data inserts, deletions, and updates, can be inaccurate, incomplete, inconsistent, or vague. There are some mechanisms and applications dedicated to discovering bugs and errors in OSM data. Such systems can remove errors through user-checks and applying predefined rules but they need an extra control process to check the real-world validity of suspected errors and bugs. This paper focuses on finding bugs and errors based on patterns and rules extracted from the tracking data of users. The underlying idea is that certain characteristics of user trajectories are directly linked to the type of feature. Using such rules, some sets of potential bugs and errors can be identified and stored for further investigations.     

Matching authority and VGI road networks using an extended node-based matching algorithm

The amount of volunteered geographic information (VGI) has increased over the past decade, and several studies have been conducted to evaluate the quality of VGI data. In this study, we evaluate the completeness of the road network in the VGI data set OpenStreetMap (OSM). The evaluation is based on an accurate and efficient network-matching algorithm. The study begins with a comparison of the two main strategies for network matching: segment-based and node-based matching. The comparison shows that the result quality is comparable for the two strategies, but the node-based result is considerably more computationally efficient. Therefore, we improve the accuracy of node-based algorithm by handling topological relationships and detecting patterns of complicated network components. Finally, we conduct a case study on the extended node-based algorithm in which we match OSM to the Swedish National Road Database (NVDB) in Scania, Sweden. The case study reveals that OSM has a completeness of 87% in the urban areas and 69% in the rural areas of Scania. The accuracy of the matching process is approximately 95%. The conclusion is that the extended node-based algorithm is sufficiently accurate and efficient for conducting surveys of the quality of OSM and other VGI road data sets in large geographic regions.     

Spatiotemporal analysis of photo contribution patterns to Panoramio and Flickr

ABSTRACT

Photo-sharing services provide a rich resource of crowdsourced spatial data consisting of georeferenced imagery and metadata. Shared photos can provide valuable information for a variety of applications and geospatial analysis tasks, such as identifying tourist hot spots or traveled routes. Understanding the spatiotemporal patterns of photo contributions will allow analysts to assess the suitability of these data for related analysis tasks. Using California as a study area, this paper analyzes various aspects of photo contribution patterns of Panoramio and Flickr. It identifies areas where annual photo contributions are still growing and areas that undergo a decline in annual contributions. Multiple regression is used to identify which environmental correlates are associated with an increase in photo-sharing activities. Furthermore, panel data of annual contributions between 2006 and 2013 for California subcounties will be used in a regression model to demonstrate that there is a positive feedback effect between Panoramio and Flickr photo contributions, but no neighborhood effect. The results of this paper provide insight into the data quality of crowdsourced image collections. These collections are commonly used for geospatial applications, including tourist information services and the computation of scenic routes.     

A geovisual analytics exploration of the OpenStreetMap crowd

It is sometimes easy to forget that massive crowdsourced data products such as Wikipedia and OpenStreetMap (OSM) are the sum of individual human efforts stemming from a variety of personal and institutional interests. We present a geovisual analytics tool called Crowd Lens for OpenStreetMap designed to help professional users of OSM make sense of the characteristics of the “crowd” that constructed OSM in specific places. The tool uses small multiple maps to visualize each contributor’s piece of the crowdsourced whole, and links OSM features with the free-form commit messages supplied by their contributors. Crowd Lens allows sorting and filtering contributors by characteristics such as number of contributions, most common language used, and OSM attribute tags applied. We describe the development and evaluation of Crowd Lens, showing how a multiple-stage user-centered design process (including testing by geospatial technology professionals) helped shape the tool’s interface and capabilities. We also present a case study using Crowd Lens to examine cities in six continents. Our findings should assist institutions deliberating OSM’s fitness for use for different applications. Crowd Lens is also potentially informative for researchers studying Internet participation divides and ways that crowdsourced products can be better comprehended with visual analytics methods.     

Description and characterization of place properties using topic modeling on georeferenced tags

ABSTRACT

User-Generated Content (UGC) provides a potential data source which can help us to better describe and understand how places are conceptualized, and in turn better represent the places in Geographic Information Science (GIScience). In this article, we aim at aggregating the shared meanings associated with places and linking these to a conceptual model of place. Our focus is on the metadata of Flickr images, in the form of locations and tags. We use topic modeling to identify regions associated with shared meanings. We choose a grid approach and generate topics associated with one or more cells using Latent Dirichlet Allocation. We analyze the sensitivity of our results to both grid resolution and the chosen number of topics using a range of measures including corpus distance and the coherence value. Using a resolution of 500 m and with 40 topics, we are able to generate meaningful topics which characterize places in London based on 954 unique tags associated with around 300,000 images and more than 7000 individuals.     

Applying VGI to collaborative research in the humanities: the case of ARTL@S

ABSTRACT

Using Artl@s as an example of a project that relies on volunteered geographic information (VGI), this article examines the specific challenges that exist, beyond those frequently discussed in general VGI systems (e.g., participants’ motivation and data quality control) in regard to sharing research data in humanities: (1) most data from the humanities is qualitative and collected from multiple data sources which are often inconsistent and unmappable; (2) data is usually interconnected with multiple relationships among different tables which creates challenges for both mapping and query functionality; (3) data is both geographical and historical. Consequently addresses that no longer exist have to be geolocated and visualized on historical basemaps and spaces must be represented diachronically; (4) the design of web map application needs to balance both sophisticated research requirements and a user-friendly interface; (5) finally contributors expect their data to be cited or acknowledged when used in other studies and users need metadata and citation information in order to reuse and repurpose datasets.

In this article, we discuss how Artl@s, a project which developed a georeferenced historical database of exhibition catalogues, addresses these challenges. Artl@s provides a case study for VGI adoption by digital humanities scholars for research data sharing, as it offers features, such as flexible batch data contribution, interrelated spatial query, automatic geolocalization of historical addresses, and data citation mechanisms.     

基于Web的志愿者地名地址数据采集与应用

地理信息数据处于动态变化之中,传统的地理信息数据采集方式由少量专业单位组织,耗时长、效率低,难以满足数据的快速采集和及时更新要求。本文介绍了基于Web平台的志愿者地名地址数据采集方案,由志愿者提交地名地址数据的网站和数据库,利用互联网的高效、开放、共享等特点,实现对海量地理数据的快速采集和更新,是一种高效低廉的地理信息数据采集方式,每个用户既是地理信息的使用者,也是地理信息的提供者,可长期低成本维持地理信息数据的现势性。     

基于遥感和GIS的环境敏感性分区研究

文章在对邹城区域生态环境状况进行分析和判别的基础上,确定了邹城环境敏感性单因子及分级依据。利用SRTM3数据,提取了邹城区域高程分级和坡度数据;利用TM遥感影像,通过监督分类和和人机交互解译方法提取植被要素和土地利用/覆被数据。结合收集到的矿产资源、自然保护及风景区及采煤塌陷风险分布专题信息建立敏感性分析数据库,使用ARCGIS平台进行空间叠加分析,得到邹城区域环境敏感性分区图。发现邹城区域重度敏感区主要分布在坡度较大、易发生水土流失地区以及山地;中度敏感区主要包括地下水源地、贡献较大的水体、自然保护区和部分塌陷风险较大的区域;轻度敏感区多为天然及人工林地。对于不同敏感级别的地区应有针对性地采取保护性开发,并在土地利用中尽量避免对重度及中度敏感区的干预。最后指出了应用RS和GIS空间信息技术进行敏感性分区的作用和意义。     

Generation of 3D virtual geographic environment based on laser scanning technique

This paper demonstrates an experiment on the generation of 3D virtual geographic environment on the basis of experimental flight laser scan-ning data by a set of algorithms and methods that were developed to auto-matically interpret range images for extracting geo-spatial features and then to reconstruct geo-objects. The algorithms and methods for the inter-pretation and modeling of laser scanner data include triangulated-irregular-net- work (TIN)-based range image inter- polation; mathematical-morphology (MM)-based range image filtering,feature extraction and range image segmentation, feature generalization and optimization, 3D objects recon-struction and modeling; computer-graphics (CG)-based visualization and animation of geographic virtual reality environment.     

Generation of 3D virtual geographic environment based on laser scanning technique

This paper demonstrates an experiment on the generation of 3D virtual geographic environment on the basis of experimental flight laser scanning data by a set of algorithms and methods that were developed to automatically interpret range images for extracting geo-spatial features and then to reconstruct geo-objects. The algorithms and methods for the interpretation and modeling of laser scanner data include triangulated-irregular-net-work (TIN)-based range image interpolation; mathematical-morphology (MM)-based range image filtering, feature extraction and range image segmentation, feature generalization and optimization, 3D objects reconstruction and modeling; computergraphics (CG)-based visualization and animation of geographic virtual reality environment.     

基于GIS-SD的大连湾水污染时空模拟与调控策略研究

大连泫可持续发展的矛盾是一个动态现象,同时这些矛盾也涉及到空间因子（例如,污染物浓度分布与环境功能区划等）。为了探讨和模拟各种发展方案（不同的经济增长和城市化）的矛盾机理,将系统动力学（ＳＤ）方法和地理信息系统（ＧＩＳ）方法结合起来,提出了一个新的可操作的ＧＩＳ－ＳＤ结合的概念框架,建立了大连湾水污染与控制系统模型,并进行了时空模拟和调控策略研究,模拟了该区域的不同增长计划（方案）对海域环境环境质     

基于GIS的农用地定级数据处理浅探

阐述了农用土地定级的意义,主要论述了GIS在农用土地定级中的应用,并以新疆巴音郭楞蒙古自治州尉犁县农用土地定级为例,探讨了利用GIS进行定级数据处理的过程和方法。进一步说明了利用GIS进行农用土地定级的优势——将定量和定位结合起来,使定级结果精确科学又能显示土地的空间属性。     

Research on the security of national geospatial data clearinghouse based on ASP

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Research on the security of national geospatial data clearinghouse based on ASP

On the basis of the authors' experiences of setting up an NGDC Web site, this paper attempts to present some significant aspects about the security of NGDC based on ASP. They include data storing, database maintenance, new technical support and so on. Firstly, this paper discusses how to provide the security of data which is saved in the hosts of NGDC. The security model of “Networks-DB Server-DB-DB Object” is also presented. In Windows NT Server, Internet Information Server (i. e., IIS) is in charge of transferring message and the management of Web sites. ASP is also based on IIS. The advantages of virtual directory technique provided by IIS are emphasized.     

论地图数据库合并技术

本文探讨了地图数据库合并技术的研究范畴、研究内容、一般数据处理流程以及与其他已有技术的关 系等一些基本问题,并给出了一个简单应用实例。这些问题的研究丰富和完善了地图数据库合并技术的基本理论 体系,对建立地图数据库合并的主要技术框架有着重要的意义。     

浅谈基础地理信息数据灾备中心的建设

简单描述了容灾备份系统的组成及其等级,对基础地理信息数据的异地备份各要素的选择及介质管理进行了研究;讨论了常见的数据库备份方式,给出了利用VTL技术进行数据库备份的具体方法,对地理信息数据的保管与维护、常见备份问题进行了分析。     

基于GIS与虚拟现实的土地利用总体规划仿真展示平台设计

土地利用总体规划的合理编制与实施,需要开放的技术平台提高公众参与度。集成应用地理信息系统(geographic information system,GIS)、虚拟现实(virtual reality,VR)及触摸屏等技术,探索了建设开放的土地利用总体规划展示平台,以直观、形象及简洁的形式向公众展现了专业的规划工作内容。研究表明:二、三维地理信息技术可与触觉等虚拟现实融合,实现了跨领域的技术创新的集成应用,创造了仿真的土地利用总体规划展示环境,实现了"图、文、数、声"一体化呈现。该平台突破传统纸质张贴形式的局限,推动了"开门"规划的实现,为提升政府部门公共服务职能提供了可借鉴的技术手段。     

基于海量地理信息的网络存储系统设计与实现

概述了合肥测绘院网络存储系统的设计与实现过程,为城市勘测单位与相关行业海量地理信息的存储提供了有效的借鉴.     

高发性流行病管理地理信息系统的设计与实现

设计并实现了高发性流行病管理信息系统,系统包含了数据管理、数据查询、数据统计、数据展示、系统管理五大模块,实现了合肥市区域范围内的高发性流行病病例基本情况的录入、编辑、存储和管理,数据详细信息的快速查询统计,数据成果在线展示等功能.     

基于遥感和GIS的水土流失因子信息提取与分级定标研究--以攀枝花市为例

以攀枝花市为例,主要选用美国陆地卫星2003年的Landsat-7 ETM+遥感数据、1∶10万地形图,运用ERDAS/IMAG INE遥感图像处理软件及M apG IS软件提取对水土流失影响较大的植被覆盖度、地形坡度、沟谷密度、土地利用类型等因子;根据中华人民共和国行业标准《土壤侵蚀分类分级标准》(SL 190-96),建立攀枝花市水土流失强度面蚀分级指标,为进一步水土流失监测研究提供科学依据。