Geotagging

Abstract: We describe Web-a-Where, a system for associating geography with Web pages. Web-a-Where locates mentions of places and determines the place each name refers to. In addition, it assigns to each page a geographic focus --- a locality that the page discusses as a whole. The tagging process is simple and fast, aimed to be applied to large collections of Web pages and to facilitate a variety of location-based applications and data analyses.Geotagging involves arbitrating two types of ambiguities: geo/non-geo and geo/geo. A geo/non-geo ambiguity occurs when a place name also has a non-geographic meaning, such as a person name (e.g., Berlin) or a common word (Turkey). Geo/geo ambiguity arises when distinct places have the same name, as in London, England vs. London, Ontario.An implementation of the tagger within the framework of the WebFountain data mining system is described, and evaluated on several corpora of real Web pages. Precision of up to 82% on individual geotags is achieved. We also evaluate the relative contribution of various heuristics the tagger employs, and evaluate the focus-finding algorithm using a corpus pretagged with localities, showing that as many as 91% of the foci reported are correct up to the country level.

Abstract: Geo-tagging is a fast-emerging trend in digital photography and community photo sharing. The presence of geographically relevant metadata with images and videos has opened up interesting research avenues within the multimedia and computer vision domains. In this paper, we survey geo-tagging related research within the context of multimedia and along three dimensions: (1) Modalities in which geographical information can be extracted, (2) Applications that can benefit from the use of geographical information, and (3) The interplay between modalities and applications. Our survey will introduce research problems and discuss significant approaches. We will discuss the nature of different modalities and lay out factors that are expected to govern the choices with respect to multimedia and vision applications. Finally, we discuss future research directions in this field.

Abstract: New web services that support user-generated and user-modified maps and spatial data are continuing to emerge at a rapid pace, as are geo-enabled digital devices that can collect and disseminate data with spatial attributes. Interactive web services such as GoogleMaps or Wikimapia allow users to create their own maps online or contribute to and edit geographic information contributed by others. Users may import or ‘mash up’ shared source codes (application programming interfaces or ‘‘APIs’’) into their own web mapping services, or use markup languages to ‘geotag’ online content such as photographs with information about their geographic location. New forms of digital spatial data are created through a growing proportion of our daily activities, such as using electronic payment cards to board a bus whose location is tracked by the public transit agency, or using GPS-enabled cell phones that trace our location and movements throughout the day. These technologies and practices are dramatically altering the contexts of geospatial data creation and sharing, the individuals and institutions who act as data producers and users, and perhaps most strikingly, geospatial data themselves. This special issue contributes to a growing body of research investigating the technological, social, and political opportunities, limitations, and implications of these phenomena. The authors examine whether existing structures and practices for spatial data collection, retrieval, validation, and dissemination are appropriate in this new context; the purposes for which these new forms of spatial data might be used; how these new technologies and practices affect (and are shaped by) the so-called ‘digital divide’; and what social and political practices may be advanced in connection with these new technologies and data. Research on these new geospatial technologies and forms of data is still nascent enough that a central line of discussion remains how to name these phenomena and the activities they enable. Terms such as neogeography (Turner 2006; Sui 2008), ubiquitous cartography (Gartner et al. 2007), and web mapping (Plewe 2007) emphasize cartographic representation, speaking to ways in which interactive web mapping services might open the practices of cartography and geospatial data creation to new actors. In contrast, others forward terms such as user-generated content (Sieber 2007), collaboratively contributed geographic information (Bishr and Mantelas this issue), and volunteered geographic information (Goodchild 2007). This second group of terms emphasizes the data themselves, highlighting shifts in the forms of spatial information that are available and in the processes through which they are created and used. These naming debates are important in part because they focus our attention on those concepts that are key to understanding this new phenomenon, and help S. Elwood (&) Department of Geography, University of Washington, Box 353550, Seattle, WA 98195, USA e-mail: selwood@u.washington.edu

Abstract: Geographical data can be obtained by converting place names from free-format text into geographical coordinates. The ability to geo-locate events in textual reports represents a valuable source of information in many real-world applications such as emergency responses, real-time social media geographical event analysis, understanding location instructions in auto-response systems and more. However, geoparsing is still widely regarded as a challenge because of domain language diversity, place name ambiguity, metonymic language and limited leveraging of context as we show in our analysis. Results to date, whilst promising, are on laboratory data and unlike in wider NLP are often not cross-compared. In this study, we evaluate and analyse the performance of a number of leading geoparsers on a number of corpora and highlight the challenges in detail. We also publish an automatically geotagged Wikipedia corpus to alleviate the dearth of (open source) corpora in this domain.