A name‐led approach to profile urban places based on geotagged Twitter data

Place is a concept that is fundamental to how we orientate and communicate space in our everyday lives. Crowdsourced social media data present a valuable opportunity to develop bottom‐up inferences of places that are integral to social activities and settings. Conventional location‐led approaches use a predefined spatial unit to associate data and space with places, which cannot capture the richness of urban places (i.e., spatial extents and their dynamic functions). This article develops a name‐led framework to overcome these limitations in using social media data to study urban places. The framework first derives place names from georeferenced Twitter data combining text mining and spatial point pattern analysis, then estimates the spatial extents by spatial clustering, and further extracts their dynamic functions with time, which makes up a complete place profile. The framework is tested on a case study in Camden Borough, London and the results are evaluated through comparisons to the Foursquare point of interest data. This name‐led approach enables the shift from space‐based analysis to place‐based analysis of urban space.     

Improving Large Area Population Mapping Using Geotweet Densities

Many different methods are used to disaggregate census data and predict population densities to construct finer scale, gridded population data sets. These methods often involve a range of high resolution geospatial covariate datasets on aspects such as urban areas, infrastructure, land cover and topography; such covariates, however, are not directly indicative of the presence of people. Here we tested the potential of geo‐located tweets from the social media application, Twitter, as a covariate in the production of population maps. The density of geo‐located tweets in 1x1 km grid cells over a 2‐month period across Indonesia, a country with one of the highest Twitter usage rates in the world, was input as a covariate into a previously published random forests‐based census disaggregation method. Comparison of internal measures of accuracy and external assessments between models built with and without the geotweets showed that increases in population mapping accuracy could be obtained using the geotweet densities as a covariate layer. The work highlights the potential for such social media‐derived data in improving our understanding of population distributions and offers promise for more dynamic mapping with such data being continually produced and freely available.     

“数字延吉”服务长吉图战略助力吉林发展

数字城市地理空间框架既是一个城市的空间基础信息平台,也是国家空间数据基础设施的基本组成部分,它是信息集成的载体、是数字城市赖以实现的不可或缺的基础支撑。本文以"数字延吉"地理空间框架建设项目的成果阐述了数字城市的建设与应用。     

Assessing the Veracity of Methods for Extracting Place Semantics from Flickr Tags

The volume and potential value of user generated content (UGC) is ever growing. Multiply sourced, its value is greatly increased by the inclusion of metadata that adequately and accurately describes that content – particularly if such data are to be integrated with more formal data sets. Typically, digital photography is tagged with location and attribute information that variously describe the location, events or objects in the image. Often inconsistent and incomplete, these attributes reflect concepts at a range of geographic scales. From a spatial data integration perspective, the information relating to “place” is of primary interest. The challenge therefore is in selecting the most appropriate tags that best describe the geography of the image. This article presents a methodology based on an information retrieval technique that separates out “place related tags” from the remainder of the tags. Different scales of geography are identified by varying the size of the sampling area within which the imagery falls. This is applied in the context of urban environments, using Flickr imagery. Empirical analysis is then used to assess the correctness of the chosen tags (i.e. whether the tag correctly describes the geographic region in which the image was taken). Logistic regression and Bayesian inference are used to attach a probability value to each place tag. The high correlation values achieved indicate that this methodology can be used to automatically select place tags for any urban region and thus hierarchically structure UGC in order that it can be semantically integrated with other data sources.     

数字马鞍山3维可视化平台的设计与实现

3维可视化平台是数字城市地理空间框架的重要组成部分,本文介绍了数字马鞍山建设中3维平台的设计与实现思路。从2,3维协同服务的角度设计了3维建设技术路线,并对海量数据传输加载及2,3维联动等关键问题提出了有益的解决方案。为其他城市建设地理空间框架提供借鉴。     

国土移动地图系统实现与技术探讨

国土移动地图系统以数字城市地理空间框架为依托,基于数字城市地理信息公共平台发布的数据服务进行开发,供国土系统各单位使用,可以更为有效地利用数字城市的建设成果,大力促进国土部门的信息化建设水平。本文旨在探讨实现该系统过程中遇到的具体问题及解决方法。     

基于平行坐标的地理空间元数据可视化检索研究

地理空间元数据具有抽象、复杂、多维的特点,而传统的元数据表达方式描述抽象,表现形式单一,表达维度有限,认知效率不高。为了提高地理空间元数据服务的效果和效率,通过引入信息可视化技术中的平行坐标方法,探究将该方法运用于地理空间元数据可视化检索的显示及交互模式。阐述基于平行坐标的地理空间元数据可视化检索原型系统的设计实现过程,通过原型系统验证该方法的可行性。     

A spatial analysis of non‐English Twitter activity in Houston,TX

The use of social media data in geographic studies has become common, yet the question of social media's validity in such contexts is often overlooked. Social media data suffers from a variety of biases and limitations; nevertheless, with a proper understanding of the drawbacks, these data can be powerful. As cities seek to become “smarter,” they can potentially use social media data to creatively address the needs of their most vulnerable groups, such as ethnic minorities. However, questions remain unanswered regarding who uses these social networking platforms, how people use these platforms, and how representative social media data is of users' everyday lives. Using several forms of regression, I explore the relationships between a conventional data source (the U.S. Census) and a subset of Twitter data potentially representative of minority groups: tweets created by users with an account language other than English. A considerable amount of non‐stationarity is uncovered, which should serve as a warning against sweeping statements regarding the demographics of users and where people prefer to post. Further, I find that precisely located Twitter data informs us more about the digital status of places and less about users' day‐to‐day travel patterns.     

数字城市地理空间信息公共平台的设计

数字城市建设的目的是实现城市各种信息的数字化共享,地理空间信息是数字城市建设的基础信息,如何实现数字城市地理空间信息的共享是数字城市建设过程中的基本问题。在以往的数字城市建设中,地理信息往往作为城市某些职能部门的“私有”信息,其共享性得不到保证,严重影响了数字城市建设。地理空间信息公共平台的设计目的是实现地理信息共享。阐述的公共平台的系统设计主要分为公共基础空间数据库的建立、地理空间信息共享环境的设计以及地理空间信息公共技术平台设计3个方面的内容。     

Extracting central places from the link structure in Wikipedia

Explicit information about places is captured in an increasing number of geospatial datasets. This article presents evidence that relationships between places can also be captured implicitly. It demonstrates that the hierarchy of central places in Germany is reflected in the link structure of the German language edition of Wikipedia. The official upper and middle centers declared, based on German spatial laws, are used as a reference dataset. The characteristics of the link structure around their Wikipedia pages, which link to each other or mention each other, and how often, are used to develop a bottom‐up method for extracting central places from Wikipedia. The method relies solely on the structure and number of links and mentions between the corresponding Wikipedia pages; no spatial information is used in the extraction process. The output of this method shows significant overlap with the official central place structure, especially for the upper centers. The results indicate that real‐world relationships are in fact reflected in the link structure on the web in the case of Wikipedia.     

数字城市公共平台数据集建设技术研究

研究探讨了数字城市公共数据集的数据类型和建库技术,实现了对数字城市地理空间框架建设涉及的多源、多尺度、多类型海量公共平台数据集的一体化存储、组织、管理和维护。     

Home range and habitat: Using platial characteristics to define urban areas from the bottom up

The spatial representation of a city is typically formed by top‐down jurisdictional boundaries. A parallel approach would be to consider representing a city based on platial characteristics, that is, a bottom‐up landscape created through individual and collectively derived representations. This study contributes to this discourse through the exploratory examination of the ecology notions of home range and habitat applied to humans in an urban context. Using spatial data collected through a WebGIS platform, we employ a spatial definition of sense of place and social capital to understand the platial nature of the city and, simultaneously, defining home range and habitat as platial notions. We found spatial variability among individual home range and habitat and the difficulty of traditional administrative boundaries to represent these areas. This research defines and presents home range and habitat to partially describe the emergent nature of platial theory and explores their operationalization at the urban level.     

Crowdsourcing functions of the living city from Twitter and Foursquare data

ABSTRACT

Urban functions are closely related to people’s spatiotemporal activity patterns, transportation needs, and a city’s business distribution and development trends. Studies investigating urban functions have used different data sources, such as remotely sensed imageries, observation, photography, and cognitive maps. However, these data sources usually suffer from low spatial, temporal, and thematic resolution. This article attempts to investigate human activities to understand urban functions through crowdsourcing social media data. In this study, we mined Twitter and Foursquare data to extract and analyze six types of human activities. The spatiotemporal analysis revealed hotspots for different activity intensities at different temporal resolution. We also applied the classified model in a real-time system to extract information of various urban functions. This study demonstrates the significance and usefulness of social sensing in analyzing urban functions. By combining different platforms of social media data and analyzing people’s geo-tagged city experience, this article contributes to leverage voluntary local knowledge to better depict human dynamics, discover spatiotemporal city characteristics, and convey information about cities.     

关于数字城市地理空间框架建设的研究

随着我国城市化进程的发展,城市规模不断扩大,传统的城市管理方法远远不能满足现代城市管理的要求。随着＂数字中国＂战略的提出,＂数字城市＂应运而生。当前以＂数字城市＂为标志的城市信息化建设正在全国范围内迅速开展,网络基础设施和空间信息基础设施是数字城市建设中两个最为重要的基础设施,而地理空间框架是空间信息基础设施的重要组成部分,是经济社会信息化发展的基础支撑平台。     

天地一体化数字影像地理空间信息的获取与更新

数字地理空间信息在经济社会发展、应急救援服务及国防军事中的作用越来越重要。网格(Grid)技术正成为继Internet和Web之后的第三代网络技术，地球空间信息网格体系的发展是对测绘科技发展的又一次机遇，航空／航天数字栅格图像数据能为现代网格地图，或无级无缝在线服务的电子地图提供丰富的动态的数据源。进入21世纪以来，多种方式的天地一体化对地观测技术体系不断发展，能全天时、快速、高精度地获取地理空间的数字影像数据。同时，为了适应不同领域和目标应用的需要，建立或更新GIS数据库的数据，图像数据处理与分析理论和方法的研究也成果斐然。     

Spatial signatures for geographic feature types: examining gazetteer ontologies using spatial statistics

Digital gazetteers play a key role in modern information systems and infrastructures. They facilitate (spatial) search, deliver contextual information to recommended systems, enrich textual information with geographical references, and provide stable identifiers to interlink actors, events, and objects by the places they interact with. Hence, it is unsurprising that gazetteers, such as GeoNames, are among the most densely interlinked hubs on the Web of Linked Data. A wide variety of digital gazetteers have been developed over the years to serve different communities and needs. These gazetteers differ in their overall coverage, underlying data sources, provided functionality, and geographic feature type ontologies. Consequently, place types that share a common name may differ substantially between gazetteers, whereas types labeled differently may, in fact, specify the same or similar places. This makes data integration and federated queries challenging, if not impossible. To further complicate the situation, most popular and widely adopted geo‐ontologies are lightweight and thus under‐specific to a degree where their alignment and matching become nothing more than educated guesses. The most promising approach to addressing this problem, and thereby enabling the meaningful integration of gazetteer data across feature types, seems to be a combination of top‐down knowledge representation with bottom‐up data‐driven techniques such as feature engineering and machine learning. In this work, we propose to derive indicative spatial signatures for geographic feature types by using spatial statistics. We discuss how to create such signatures by feature engineering and demonstrate how the signatures can be applied to better understand the differences and commonalities of three major gazetteers, namely DBpedia Places, GeoNames, and TGN.     

构建智能交通地理信息及定位平台

计算机技术、通信技术、现代控制技术、全球定位技术和地理信息系统技术为智能交通系统 (ITS)的建设提供了可靠的技术支撑。描述地球表面的基础地理信息数据是国家空间数据基础设施建设中的重要组成部分。交通地理信息及定位平台是面向交通运输 ,以地理信息系统和空间定位技术为依托的广泛概念 ,构架交通地理信息及定位平台 ,提供车辆在四维时空中的位置和有关空间目标描述的技术和信息 ,为实现交通智能化奠定基础。     

武汉市地理空间信息共享服务平台的建设与应用

武汉市地理空间信息共享服务平台建设是"数字武汉空间数据基础设施"建设的核心内容.该平台按照"数字城市"的理念和框架,集成了武汉市多源、多尺度、多时态的空间数据,实现了跨部门、跨平台的空间信息共享共用,为政府部门和相关行业提供在线的地理信息网络服务,在武汉市经济社会发展和和谐社会建设中得到了广泛应用.     

面向持续交付的空间大数据基础设施设计与实现

随着空间大数据技术的快速发展,越来越多与空间大数据云平台相关的项目逐步规划和建立.GIS建设项目已经朝着平台化、虚拟化和智能化的方向转变.新一代GIS平台建设的重要原则之一,就是要把空间大数据作为企业的重要资产.它需要系统地管理、持续地维护、安全地控制以及深入地挖掘.在持续探索数据价值的过程中,对平台基础设施提出了新的技术要求,包括集成多种开源技术、支持快速的迭代开发、支持持续运行的数据分析任务等.本文研究的重点是结合DevOps等先进的面向持续交付的管理理念,利用相关技术提出空间大数据基础设施的设计方案,使其具备持续交付能力.     

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.