Publishing Reference Geodata on the Web : Opportunities and Challenges for IGN France

International audienceThe French national mapping agency (IGN) produces several different but complementary geographic vector reference databases delivered in traditional GIS formats. However, linked data users have different expectations and habits, such as the need to browse an entire data catalogue in RDF using the "follow-your-nose" navigation capacity from one graph to another. Besides, traditional GIS data formats are not interoperable with RDF. Yet, all these geographic datasets could be used with benefits on the Web of data, either with direct georeferencing through geographic primitives, or indirect one through postal addresses. In this paper, we aim to contribute to the georeferencing of datasets published on the Web of data by providing such resources for French context. Firstly, we propose two vocabularies designed for representing structured geometries defined with coordinates expressed in any Coordinates Reference System (CRS). Secondly, we reuse these vocabularies and the CRSs' dataset to publish a reference dataset on administrative units that can also be reused for indirect georeferencing purposes. Finally , we also propose two vocabularies for describing geographic feature types. In addition to these resources, we also present a comprehensive workflow for easily publishing geographic data on the Web of data

Best Practices for Publishing, Retrieving, and Using Spatial Data on the Web

Data owners are creating an ever richer set of information resources online, and these are being used for more and more applications. With the rapid growth of connected embedded devices, GPS-enabled mobile devices, and various organizations that publish their location-based data (i.e., weather and traffic services), maps and geographical and spatial information (i.e., GIS and open maps), spatial data on the Web is becoming ubiquitous and voluminous. However, the heterogeneity of the available spatial data, as well as some challenges related to spatial data in particular make it difficult for data users, web applications and services to discover, interpret and use the information in large and distributed web systems. This paper summarizes some of the efforts that have been undertaken in the joint W3C/OGC Working Group on Spatial Data on the Web, in particular the effort to describe the best practices for publishing spatial data on the Web. This paper presents the set of principles that guide the selection of these best practices, describes best practices that are employed to enable publishing, discovery and retrieving (querying) this type of data on the Web, and identifies some areas where a best practice has not yet emerged

Assessing the Positional Planimetric Accuracy of DBpedia Georeferenced Resources

International audienceAssessing the quality of the main linked data sources on the Web like DBpedia or Yago is an important research topic. The existing approaches for quality assessment mostly focus on determining whether data sources are compliant with Web of data best practices or on their completeness, semantic accuracy, consistency, relevancy or trustworthi-ness. In this article, we aim at assessing the accuracy of a particular type of information often associated with Web of data resources: direct spatial references. We present the approaches currently used for assessing the planimetric accuracy of geographic databases. We explain why they cannot be directly applied to the resources of the Web of data. Eventually , we propose an approach for assessing the planimetric accuracy of DBpedia resources, adapted to the open nature of this knowledge base

LocLinkVis: A Geographic Information Retrieval-Based System for Large-Scale Exploratory Search

In this paper we present LocLinkVis (Locate-Link-Visualize); a system which supports exploratory information access to a document collection based on geo-referencing and visualization. It uses a gazetteer which contains representations of places ranging from countries to buildings, and that is used to recognize toponyms, disambiguate them into places, and to visualize the resulting spatial footprints.Comment: SEM'1

Geographical information retrieval with ontologies of place

Geographical context is required of many information retrieval tasks in which the target of the search may be documents, images or records which are referenced to geographical space only by means of place names. Often there may be an imprecise match between the query name and the names associated with candidate sources of information. There is a need therefore for geographical information retrieval facilities that can rank the relevance of candidate information with respect to geographical closeness of place as well as semantic closeness with respect to the information of interest. Here we present an ontology of place that combines limited coordinate data with semantic and qualitative spatial relationships between places. This parsimonious model of geographical place supports maintenance of knowledge of place names that relate to extensive regions of the Earth at multiple levels of granularity. The ontology has been implemented with a semantic modelling system linking non-spatial conceptual hierarchies with the place ontology. An hierarchical spatial distance measure is combined with Euclidean distance between place centroids to create a hybrid spatial distance measure. This is integrated with thematic distance, based on classification semantics, to create an integrated semantic closeness measure that can be used for a relevance ranking of retrieved objects

Automated Knowledge Generation with Persistent Surveillance Video

The Air Force has increasingly invested in persistent surveillance platforms gathering a large amount of surveillance video. Ordinarily, intelligence analysts watch the video to determine if suspicious activities are occurring. This approach to video analysis can be a very time and manpower intensive process. Instead, this thesis proposes that by using tracks generated from persistent video, we can build a model to detect events for an intelligence analyst. The event that we chose to detect was a suspicious surveillance activity known as a casing event. To test our model we used Global Positioning System (GPS) tracks generated from vehicles driving in an urban area. The results show that over 400 vehicles can be monitored simultaneously in real-time and casing events are detected with high probability (43 of 43 events detected with only 4 false positives). Casing event detections are augmented by determining which buildings are being targeted. In addition, persistent surveillance video is used to construct a social network from vehicle tracks based on the interactions of those tracks. Social networks that are constructed give us further information about the suspicious actors flagged by the casing event detector by telling us who the suspicious actor has interacted with and what buildings they have visited. The end result is a process that automatically generates information from persistent surveillance video providing additional knowledge and understanding to intelligence analysts about terrorist activities

Semantic Markup for Geographic Web Maps in HTML

In the recent years more and more geographical web maps have been developed and published on the Open Web Platform. Technically this has turned all variants of these maps into documents of the Hypertext Markup Language (HTML) making them appear to us naturally as graph-like and semi-structured data. In this dispute with geographical web maps and HTML we draw on the notion of so called “map mashups”. Requiring an alternative model and definition of what such a map is, our research allows us to build and refine supportive technology which helps us in analyzing and interpreting information map makers code into their visualizations. The spectacles we take on to shine light on the current authoring practices behind many geographical web maps are informed by the perspective of a “critical map reader”. A task-oriented conception of “map critique” helped us to deduce a meaningful user perspective from which we specifically call the semantic web community for support on how to represent various information presented in maps from many authors and sources. With this perspective and questions in mind we investigated the Schema.org vocabulary as an ontology to use for turning elements of geographic web maps into textual statements referencing entities in the “outer world”. To illustrate and to make our investigation of the corresponding web standard documents easily applicable for map makers, to open up the discussion, but also to challenge and develop our first conclusions, we implemented them as a minimal extension to the standard API of the LeafletJS open source web mapping library