A Temporal Approach to Defining Place Types based on User-Contributed Geosocial Content

Place is one of the foundational concepts on which the field of Geography has been built. Traditionally, GIScience research into place has been approached from a spatial perspective. While space is an integral feature of place, it represents only a single dimension (or a combination of three dimensions to be exact), in the complex, multidimensional concept that is place. Though existing research has shown that both spatial and thematic dimensions are valuable, time has historically been under-utilized in its ability to describe and define places and their types. The recent availability and access to user-generated geosocial content has allowed for a much deeper investigation of the temporal dimension of place. Multi-resolution temporal signatures are constructed based on these data permitting both place instances and place types to be compared through a robust set of (dis)similarity measures. The primary contribution of this work lies in demonstrating how places are defined through a better understanding of temporal user behavior. Furthermore, the results of this research present the argument that the temporal dimension is the most indicative placial dimension for classifying places by type

Assessing spatiotemporal predictability of LBSN : a case study of three Foursquare datasets

Location-based social networks (LBSN) have provided new possibilities for researchers to gain knowledge about human spatiotemporal behavior, and to make predictions about how people might behave through space and time in the future. An important requirement of successfully utilizing LBSN in these regards is a thorough understanding of the respective datasets, including their inherent potential as well as their limitations. Specifically, when it comes to predictions, we must know what we can actually expect from the data, and how we could maximize their usefulness. Yet, this knowledge is still largely lacking from the literature. Hence, this work explores one particular aspect which is the theoretical predictability of LBSN datasets. The uncovered predictability is represented with an interval. The lower bound of the interval corresponds to the amount of regular behaviors that can easily be anticipated, and represents the correct predication rate that any algorithm should be able to achieve. The upper bound corresponds to the amount of information that is contained in the dataset, and represents the maximum correct prediction rate that cannot be exceeded by any algorithms. Three Foursquare datasets from three American cities are studied as an example. It is found that, within our investigated datasets, the lower bound of predictability of the human spatiotemporal behavior is 27%, and the upper bound is 92%. Hence, the inherent potentials of the dataset for predicting human spatiotemporal behavior are clarified, and the revealed interval allows a realistic assessment of the quality of predictions and thus of associated algorithms. Additionally, in order to provide further insight into the practical use of the dataset, the relationship between the predictability and the check-in frequencies are investigated from three different perspectives. It was found that the individual perspective provides no significant correlations between the predictability and the check-in frequency. In contrast, the same two quantities are found to be negatively correlated from temporal and spatial perspectives. Our study further indicates that the heavily frequented contexts and some extraordinary geographic features such as airports could be good starting points for effective improvements of prediction algorithms. In general, this research provides novel knowledge regarding the nature of the LBSN dataset and practical insights for a more reasonable utilization of the dataset

Spatio-semantic user profiles in location-based social networks

Knowledge of users’ visits to places is one of the keys to understanding their interest in places. User-contributed annotations of place, the types of places they visit, and the activities they carry out, add a layer of important semantics that, if considered, can result in more refined representations of user profiles. In this paper, semantic information is summarised as tags for places and a folksonomy data model is used to represent spatial and semantic relationships between users, places, and tags. The model allows simple co-occurrence methods and similarity measures to be applied to build different views of personalised user profiles. Basic profiles capture direct user interactions, while enriched profiles offer an extended view of users’ association with places and tags that take into account relationships in the folksonomy. The main contributions of this work are the proposal of a uniform approach to the creation of user profiles on the Social Web that integrates both the spatial and semantic components of user-provided information, and the demonstration of the effectiveness of this approach with realistic datasets

Extracting Computational Representations of Place with Social Sensing

Place-based GIS are at the forefront of GIScience research and characterized by textual descriptions, human conceptualizations as well as the spatial-semantic relationships among places. The concepts of places are difficult to handle in geographic information science and systems because of their intrinsic vagueness. They arise from the complex interaction of individuals, society, and the environment. The exact delineation of vague regions is challenging as their borders are vague and the membership within a region varies non-monotonically and as a function of context. Consequently, vague regions are difficult to handle computationally, e.g., in spatial analysis, cartography, geographic information retrieval, and GIS workflows in general. The emergence of big data brings new opportunities for us to understand the place semantics from large-scale volunteered geographic information and data streams, such as geotags, texts, activity streams, and GPS trajectories. The term "social sensing" describes such individual-level big geospatial data and the associated analysis methods. In this dissertation, I present a generalizable, data-driven framework that complements classical top-down approaches by extracting the representations of vague cognitive regions and function regions from bottom-up approaches using spatial statistics and machine learning techniques with various social sensing sources. I demonstrate how to derive crisp boundaries for cognitive and functional regions from points of interest data, and show how natural language processing techniques can enrich our understanding of places and form a foundation for the semantic characterization of place types and the generalization of regions. This work makes contributions to the development of computational methodologies for extracting vague cognitive regions and functional regions using data-driven approaches as well as the novel semantic generalization processing technique

Geospatial Semantics

Geospatial semantics is a broad field that involves a variety of research areas. The term semantics refers to the meaning of things, and is in contrast with the term syntactics. Accordingly, studies on geospatial semantics usually focus on understanding the meaning of geographic entities as well as their counterparts in the cognitive and digital world, such as cognitive geographic concepts and digital gazetteers. Geospatial semantics can also facilitate the design of geographic information systems (GIS) by enhancing the interoperability of distributed systems and developing more intelligent interfaces for user interactions. During the past years, a lot of research has been conducted, approaching geospatial semantics from different perspectives, using a variety of methods, and targeting different problems. Meanwhile, the arrival of big geo data, especially the large amount of unstructured text data on the Web, and the fast development of natural language processing methods enable new research directions in geospatial semantics. This chapter, therefore, provides a systematic review on the existing geospatial semantic research. Six major research areas are identified and discussed, including semantic interoperability, digital gazetteers, geographic information retrieval, geospatial Semantic Web, place semantics, and cognitive geographic concepts.Comment: Yingjie Hu (2017). Geospatial Semantics. In Bo Huang, Thomas J. Cova, and Ming-Hsiang Tsou et al. (Eds): Comprehensive Geographic Information Systems, Elsevier. Oxford, U

Parsing Perceptions of Place: Locative and Textual Representations of Place Émilie-Gamelin on Twitter

We increasingly engage in geographies mediated by social media, which is changing how we experience and produce places. This raises questions about how ‘place’ is conceived and received in networked virtual spaces. Place has remained difficult to grasp in both geography and communications studies that utilize social media data. To attend to this, I first develop a conceptual framework that bridges the phenomenology of spatiality with the communication of place. I then present a case study of Place Émilie-Gamelin in Montreal: a plaza located atop the city’s busiest transit hub. Despite its geographic centrality, it is a liminal space appropriated by marginalized groups and contentious political movements. Since 2015, it has been subject to a city-led revitalization program with intentions of attracting party-goers and tourists. Using a communications geography framework, I collected a year’s worth of tweets, first, employing a filter to capture georeferenced tweets in and around the study site, and second, using the site’s toponyms to retrieve tweets through textual queries. To understand these representations, I coded them by relevance, theme and communicative function. Results showed a place evolving in scope, name and meaning, reflecting diverging flows and uses. I found that there were more textual connotations of the study site than there were geotweets, and that the former were more diverse in their representation of place. The thesis demonstrates how promotional content on Twitter should be more critically analyzed in concert with expressive and descriptive tweets and geotweets, and that this implies spatial ontologies and data collection methods that consider a place on social media as a discursive construction. This is especially so since Twitter has become increasingly ‘platial’ through internal changes and its entwinement with other social media platforms: changes which require consideration in all Twitter-based spatial and textual analyses. The study provides an updated perspective on Twitter’s use in the spatial humanities, GIScience and geography and contributes to those interested in applying more nuanced cartographies of places

Parsing Perceptions of Place: Locative and Textual Representations of Place Émilie-Gamelin on Twitter

We increasingly engage in geographies mediated by social media, which is changing how we experience and produce places. This raises questions about how ‘place’ is conceived and received in networked virtual spaces. Place has remained difficult to grasp in both geography and communications studies that utilize social media data. To attend to this, I first develop a conceptual framework that bridges the phenomenology of spatiality with the communication of place. I then present a case study of Place Émilie-Gamelin in Montreal: a plaza located atop the city’s busiest transit hub. Despite its geographic centrality, it is a liminal space appropriated by marginalized groups and contentious political movements. Since 2015, it has been subject to a city-led revitalization program with intentions of attracting party-goers and tourists. Using a communications geography framework, I collected a year’s worth of tweets, first, employing a filter to capture georeferenced tweets in and around the study site, and second, using the site’s toponyms to retrieve tweets through textual queries. To understand these representations, I coded them by relevance, theme and communicative function. Results showed a place evolving in scope, name and meaning, reflecting diverging flows and uses. I found that there were more textual connotations of the study site than there were geotweets, and that the former were more diverse in their representation of place. The thesis demonstrates how promotional content on Twitter should be more critically analyzed in concert with expressive and descriptive tweets and geotweets, and that this implies spatial ontologies and data collection methods that consider a place on social media as a discursive construction. This is especially so since Twitter has become increasingly ‘platial’ through internal changes and its entwinement with other social media platforms: changes which require consideration in all Twitter-based spatial and textual analyses. The study provides an updated perspective on Twitter’s use in the spatial humanities, GIScience and geography and contributes to those interested in applying more nuanced cartographies of places

Conflating point of interest (POI) data: A systematic review of matching methods

Point of interest (POI) data provide digital representations of places in the real world, and have been increasingly used to understand human-place interactions, support urban management, and build smart cities. Many POI datasets have been developed, which often have different geographic coverages, attribute focuses, and data quality. From time to time, researchers may need to conflate two or more POI datasets in order to build a better representation of the places in the study areas. While various POI conflation methods have been developed, there lacks a systematic review, and consequently, it is difficult for researchers new to POI conflation to quickly grasp and use these existing methods. This paper fills such a gap. Following the protocol of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), we conduct a systematic review by searching through three bibliographic databases using reproducible syntax to identify related studies. We then focus on a main step of POI conflation, i.e., POI matching, and systematically summarize and categorize the identified methods. Current limitations and future opportunities are discussed afterwards. We hope that this review can provide some guidance for researchers interested in conflating POI datasets for their research

Spatiotemporal user and place modelling on the geo-social web

Users of Location-Based Social Networks (LBSN) are giving away information about their whereabouts, and their interactions in the geographic space. In comparison to other types of personal data, location data are sensitive and can reveal user’s daily routines, activities, experiences and interests in the physical world. As a result, the user is facing an information overload that overburdens him to make a satisfied decision on where to go or what to do in a place. Thus, finding the matching places, users and content is one of the key challenges in LSBNs. This thesis investigates the different dimensions of data collected on LBSNs and proposes a user and place modelling framework. In particular, this thesis proposes a novel approach for the construction of different views of personal user profiles that reflect their interest in geographic places, and how they interact with geographic places. Three novel modelling frameworks are proposed, the static user model, the dynamic user model and the semantic place model. The static user model is a basic model that is used to represent the overall user interactions towards places. On the other hand, the dynamic user model captures the change of the user’s preferences over time. The semantic place model identifies user activities in places and models the relationships between places, users, implicit place types, and implicit activities. The proposed models demonstrate how geographic place characteristics as well as implicit user interactions in the physical space can further enrich the user profiles. The enrichment method proposed is a novel method that combines the semantic and the spatial influences into user profiles. Evaluation of the proposed methods is carried out using realistic data sets collected from the Foursquare LBSN. A new Location and content recommendation methods are designed and implemented to enhance existing location recommendation methods and results showed the usefulness of considering place semantics and the time dimension when the proposed user profiles in recommending locations and content. The thesis considers two further related problems; namely, the construction of dynamic place profiles and computing the similarity between users on LBSN. Dynamic place profiles are representations of geographic places through users’ interaction with the places. In comparison to static place models represented in gazetteers and map databases, these place profiles provide a dynamic view of how the places are used by actual people visiting and interacting with places on the LBSN. The different views of personal user profiles constructed within our framework are used for computing the similarity between users on the LBSN. Temporal user similarities on both the semantic and spatial levels are proposed and evaluated. Results of this work show the challenges and potential of the user data collected on LBSN

Approaching location-based services from a place-based perspective: from data to services?

Despite the seemingly obvious importance of a link between notions of place and the provision of context in location-based services (LBS), truly place-based LBS remain rare. Place is attractive as a concept for designing services as it focuses on ways in which people, rather than machines, represent and talk about places. We review papers which have extracted place-relevant information from a variety of sources, examining their rationales, the data sources used, the characteristics of the data under study and the ways in which place is represented. Although the data sources used are subject to a wide range of biases, we find that existing methods and data sources are capable of extracting a wide range of place-related information. We suggest categories of LBS which could profit from such information, for example, by using place-related natural language (e.g. vernacular placenames) in tracking and routing services and moving the focus from geometry to place semantics in location-based retrieval. A key future challenge will be to integrate data derived from multiple sources if we are to advance from individual case studies focusing on a single aspect of place to services which can deal with multiple aspects of place