Now showing 1 - 9 of 9
  • Publication
    An open-source web architecture for adaptive location-based services
    (International Society for Photogrammetry and Remote Sensing, 2010) ; ; ;
    As the volume of information available online continues to grow, there is an increasing problem with information overload. This issue is also escalating in the spatial domain as the amount of geo-tagged information expands. With such an abundance of geo-information, it is difficult for map users to find content that is relevant to them. The problem is intensified when considering Location-Based Services. These services, which are dependent upon a user’s geographic location, generally operate on portable devices. These devices have a reduced screen size coupled with a limited processing power and so the need to provide personalised content is of paramount importance. Our previous work has focused on examining techniques to determine user interests in order to provide adapted and personalised map content which is suitable to display on portable devices. In this paper, in order to reduce the processing load on the user’s device, a novel client server architecture is employed. The framework is designed using open-source, web-based technologies which monitor user locations and interactions with map content overtime to produce a user profile. This profile is then used to render personalised maps. By utilising the power of web-based technologies in an innovative manner, any operational issues between different mobile devices is alleviated, as the device only requires a web-browser to receive map content. This article describes the techniques, architecture and technologies used to achieve this.
  • Publication
    Urban Consumption Patterns: OpenStreetMap Quality for Social Science Research
    Citizen consumption refers to the goods and services which citizens utilise. This includes time spent on leisure and cultural activities as well as the consumption of necessary and luxury goods and services. The spatial dimension of consumption inequality can show the underlying urban spatial structure and processes of a city. Usually, the main barrier to effectively measuring consumption is the availability and accessibility of spatial data. While the main body of the literature utilises official, government data, such data is not always available, up-to-date or can be costly to acquire. In this paper, we discuss the potential of Volunteered Geographic Information (VGI) as a source of spatial data for determining consumption inequality. To this end, we compared OpenStreetMap (OSM) data, that can be used as proxies for consumption inequality, with official data in the area of Greater London. The results show that OSM is currently inadequate for studying the spatial dimension of consumption. It is our view that while VGI is appropriate for tasks such as routing and navigation, it also has the potential to add value to social science studies in the future.
  • Publication
    Computing the semantic similarity of geographic terms using volunteered lexical definitions
    Volunteered geographic information (VGI) is generated by heterogenous ‘information communities’ that co-operate to produce reusable units of geographic knowledge. A consensual lexicon is a key factor to enable this open production model. Lexical definitions help demarcate the boundaries of terms, forming a thin semantic ground on which knowledge can travel. In VGI, lexical definitions often appear to be inconsistent, circular, noisy and highly idiosyncratic. Computing the semantic similarity of these ‘volunteered lexical definitions’ has a wide range of applications in GIScience, including information retrieval, data mining and information integration. This article describes a knowledge-based approach to quantify the semantic similarity of lexical definitions. Grounded in the recursive intuition that similar terms are described using similar terms, the approach relies on paraphrase-detection techniques and the lexical database WordNet. The cognitive plausibility of the approach is evaluated in the context of the OpenStreetMap (OSM) Semantic Network, obtaining high correlation with human judgements. Guidelines are provided for the practical usage of the approach.
      627Scopus© Citations 43
  • Publication
    Semantically enriching VGI in support of implicit feedback analysis
    (Springer-Verlag, 2011-03) ;
    In recent years, the proliferation of Volunteered Geographic Information (VGI) has enabled many Internet users to contribute to the construction of rich and increasingly complex spatial datasets. This growth of geo-referenced information and the often loose semantic structure of such data have resulted in spatial information overload. For this reason, a semantic gap has emerged between unstructured geo-spatial datasets and high-level ontological concepts. Filling this semantic gap can help reduce spatial information overload, therefore facilitating both user interactions and the analysis of such interaction. Implicit Feedback analysis is the focus of our work. In this paper we address this problem by proposing a system that executes spatial discovery queries. Our system combines a semantically-rich and spatially-poor ontology (DBpedia) with a spatially-rich and semantically-poor VGI dataset (OpenStreetMap). This technique differs from existing ones, such as the aggregated dataset LinkedGeoData, as it is focused on user interest analysis and takes map scale into account. System architecture, functionality and preliminary results gathered about the system performance are discussed.
      1034Scopus© Citations 33
  • Publication
    The Similarity Jury: Combining expert judgements on geographic concepts
    A cognitively plausible measure of semantic similarity between geographic concepts is valuable across several areas, including geographic information retrieval, data mining, and ontology alignment. Semantic similarity measures are not intrinsically right or wrong, but obtain a certain degree of cognitive plausibility in the context of a given application. A similarity measure can therefore be seen as a domain expert summoned to judge the similarity of a pair of concepts according to her subjective set of beliefs, perceptions, hypotheses, and epistemic biases. Following this analogy, we first define the similarity jury as a panel of experts having to reach a decision on the semantic similarity of a set of geographic concepts. Second, we have conducted an evaluation of 8 WordNet-based semantic similarity measures on a subset of OpenStreetMap geographic concepts. This empirical evidence indicates that a jury tends to perform better than individual experts, but the best expert often outperforms the jury. In some cases, the jury obtains higher cognitive plausibility than its best expert.
      625Scopus© Citations 7
  • Publication
    A holistic semantic similarity measure for viewports in interactive maps
    In recent years, geographic information has entered the mainstream, deeply altering the pre-existing patterns of its production, distribution, and consumption. Through web mapping, millions of online users utilise spatial data in interactive digital maps. The typical unit of visualisation of geo-data is a viewport, defined as a bi-dimensional image of a map, fixed at a given scale, in a rectangular frame. In a viewport, the user performs analytical tasks, observing individual map features, or drawing high-level judgements about the objects in the viewport as a whole. Current geographic information retrieval (GIR) systems aim at facilitating analytical tasks, and little emphasis is put on the retrieval and indexing of visualised units, i.e. viewports. In this paper we outline a holistic, viewport-based GIR system, offering an alternative approach to feature-based GIR. Such a system indexes viewports, rather than individual map features, extracting descriptors of their high-level, overall semantics in a vector space model. This approach allows for efficient comparison, classification, clustering, and indexing of viewports. A case study describes in detail how our GIR system models viewports representing geographical locations in Ireland. The results indicate advantages and limitations of the viewport-based approach, which allows for a novel exploration of geographic data, using holistic semantics.
      500Scopus© Citations 7
  • Publication
    A comparison of open source geospatial technologies for web mapping
    The past decade has witnessed a steady growth of open source software usage in industry and academia, leading to a complex ecosystem of projects. Web and subsequently geographical information systems have become prominent technologies, widely adopted in diverse domains. Within this context, we developed an open source web platform for interoperable GIServices. In order to implement this architecture, 14 projects were selected and analysed, including the client-side libraries and the server-side components. Although other surveys have been conducted in this area, little feedback has been formally obtained from the users and developers concerning their opinion of these tools. A questionnaire was designed to obtain responses from the relevant online communities about a given set of characteristics. This article describes the technologies and reports the results of the survey, providing first-hand information about open source web and geospatial tools.
      1487Scopus© Citations 11
  • Publication
    Geographic Knowledge Extraction and Semantic Similarity in OpenStreetMap
    In recent years, a web phenomenon known as Volunteered Geographic Information (VGI) has produced large crowdsourced geographic data sets. OpenStreetMap (OSM), the leading VGI project, aims at building an open-content world map through user contributions. OSM semantics consists of a set of properties (called 'tags') describing geographic classes, whose usage is defined by project contributors on a dedicated Wiki website. Because of its simple and open semantic structure, the OSM approach often results in noisy and ambiguous data, limiting its usability for analysis in information retrieval, recommender systems and data mining. Devising a mechanism for computing the semantic similarity of the OSM geographic classes can help alleviate this semantic gap. The contribution of this paper is twofold. It consists of (1) the development of the OSM Semantic Network by means of a web crawler tailored to the OSM Wiki website; this semantic network can be used to compute semantic similarity through co-citation measures, providing a novel semantic tool for OSM and GIS communities; (2) a study of the cognitive plausibility (i.e. the ability to replicate human judgement) of co-citation algorithms when applied to the computation of semantic similarity of geographic concepts. Empirical evidence supports the usage of co-citation algorithms-SimRank showing the highest plausibility-to compute concept similarity in a crowdsourced semantic network.
      1633Scopus© Citations 106
  • Publication
    RecoMap : an interactive and adaptive map-based recommender
    (ACM Special Interest Group on Applied Computing, 2010-03) ; ; ;
    With the growing availability of geo-referenced information on the Web, the problem of spatial information overload has attracted interest both in the commercial and academic world. In order to tackle this issue, personalisation techniques can be used to tailor spatial contents based upon user interests. RecoMap, the system described in this paper, deducts user interests by monitoring user interaction and context to provide personalised spatial recommendations. After an overview of existing recommendation systems within the geospatial domain, the novel approach adopted by RecoMap to produce such recommendations is described. A case study related to a university campus setting is used to outline an application of this technique. Details of the implementation and initial testing of this prototype are provided.
      630Scopus© Citations 26