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Improving volunteered geographic data quality using semantic similarity measurements
 

Improving volunteered geographic data quality using semantic similarity measurements

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    Improving volunteered geographic data quality using semantic similarity measurements Improving volunteered geographic data quality using semantic similarity measurements Presentation Transcript

    • 1/26 Improving volunteered geographic data qualityImproving volunteered geographic data quality using semantic similarity measurementsusing semantic similarity measurements Arnaud Vandecasteele -Arnaud Vandecasteele - Rodolphe DevillersRodolphe Devillers Memorial University of Newfoundland, CanadaMemorial University of Newfoundland, Canada 8th International Symposium on Spatial Data Quality, 30 May - 1 June 2013
    • 2/26 Outline Introduction Conclusion Semantic Similarity P-Rank algorithm Tobler's Law OSM Semantic Plugin Description Examples
    • 3/26 Introduction National Mapping Agencies What make National Mapping Agencies Authoritative ? Positional Accuracy Completeness Attribute Accuracy ISO 19113 ISO 19115 ... ISO 19157
    • 4/26 Introduction Geographic Information Quality view as a Project Management Triangle
    • 5/26 Introduction Geographic Information Quality view as a Project Management Triangle Really?
    • 6/26 Introduction Could Another Map be authoritative* ? * and cheap, and fast, accurate and in the better of worlds free
    • 7/26 Introduction Volunteered Geographic Information (VGI)
    • 8/26 Introduction Volunteered Geographic Information (VGI) the widespread engagement of large numbers of private citizens, often with little in the way of formal qualifications, in the creation of geographic information “ Goodchild - 2007 ”
    • 9/26 Source: http://wiki.openstreetmap.org/wiki/Stats OpenStreetMap (OSM) is a collaborative project to create a free editable map of the world + 1 million + 1.8 billion nodes + 180 million ways + 1.9 million relations Started in 2004 Introduction The OpenStreetMap project
    • 10/26 Introduction Data Quality & Volunteered Geographic Information What about Data Quality ? Good geometric accuracy Haklay – 2010, Girres and Touya – 2010, Ludwig et al., - 2011 But Geographic coverage patchwork Goodchild - 2007 Semantics can be inconsistent Ballatore et al., - 2012, Mooney and Corcoran - 2012
    • 11/26 Introduction VGI changed the way we produce, publish and share Geographic Information BUT Semantic Quality is still an important issue How to improve semantic quality using a VGI approach ? Research Problem
    • 12/26 Semantic Similarity What is Semantic Similarity ? Landuse = Forest How to describe a forest in OpenStreetMap Natural = Wood One concept, different representation ! Q ? -> When should we use landuse=forest rather than natural=wood? * https://help.openstreetmap.org/questions/324/when-should-we-use-landuseforest-rather-than-naturalwood 11 different answers and no real general agreement
    • 13/26 Semantic Similarity How to measure the semantic similarity ? ● Geometric Model ● Feature Model ● Alignment Model ● Network models ● Transformation Model Different models exist: Semantic similarity applied to VGI: Mooney and Corcoran - 2012 Ballatore et al., - 2012 Natural = Wood Landuse = Forest Natural = Wood Landuse = Forest Natural = Wood Landuse = Forest Measure? Semantic Network created from the OpenStreetMap Wiki Point Pattern analysis and semantic pattern
    • 14/26 Semantic Similarity Semantic Network from the OSM Wiki, who it works ?
    • 15/26 Source: OSM WIKI Semantic Similarity Semantic Network from the OSM Wiki
    • 16/26 Measuring Semantic similarity Two entities are similar if : 1 They are referenced by similar entities 2 They reference similar entities A B C = A B C = Semantic Similarity P-Rank Algorithm
    • 17/26 Semantic similarity all things are related, but nearbynearby things are more relatedrelated than distant things “ ”Tobler - 1970 Semantic similarity and Geography Tobler's first law of geography
    • 18/26 New Object in a cityNew Object in a cityA P-Rank score P-Rankscore P-Rank score P-Rankscore P-Rank score P-Rank score Semantic similarity Applied Tobler's first law to semantic similarity
    • 19/26 Java OpenStreetMap Editor OpenStreetMap Semantic Plugin OSM Editor usage stats (source OSM Wiki)
    • 20/26 Description OpenStreetMap Semantic Plugin
    • 21/26 A B P-Rank Score 0.18 A C P-Rank Score 0.35 A D P-Rank Score 0.05 How similar are they ? P-Rank scores OpenStreetMap Semantic Plugin (aka OSMantic) Description A AC
    • 22/26 Creation of a new object Examples - Creation of a new object New object
    • 23/26 OpenStreetMap Semantic Plugin Examples - Edition of an existing object
    • 24/26 OpenStreetMap Semantic Plugin Examples – Semantic Similarity Evaluation
    • 25/26 Conclusion The next big question ? When will VGI be the next authoritative dataset ? Semantic Similarity can be used to enhance the quality of VGI dataset OSM Semantic plugin uses a collaborative approach to reduce the potential semantic similarity How to improve the results: ● Using the Tag Info database to know the most used tags ● By mixing the Geographic and the semantic approach (Ballatore + Mooney)
    • 26/26 Questions ? Rodolphe Devillers Marine Geomatics Lab http://www.marinegis.com/ Memorial University of Newfoundland Acknowledgements Natural Science and Engineering Research Council of Canada (NSERC) Andrea Ballatore for sharing his results