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Surveying GeoNames
Gazetteer Data for the Nordic Countries
Dirk Ahlers
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Motivation Location information is vital for many
applications Gazetteers provide basic geospatial
knowledge Quality is often only implicitly assumed Quality indicators are needed
NIK 2015
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Gazetteers Geographical Thesaurus
Coordinates, name, type, hierarchy, population, … Main data source for geoparsing and subsequent
geocoding, ‘what is around’ location finding etc. Data sources
GeoNames.org Large worldwide coverage, freely available
TGN – The Getty Thesaurus of Geographic Names Used in museums, license needed. New: LOD
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Nordic Countries Denmark (DK)
Faroe Islands (FO) and Greenland (GL)
Finland (FI) Åland Islands (AX)
Iceland (IS) Sweden (SE) Norway (NO)
Svalbard and Jan Mayen (SJ) [plus Antarctic territories]
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Comparison GeoNames-TGN
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Mapping all places
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Populated places
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Anomalies Geospatial irregularities
Both large-scale and small-scale Also in metadata
Simplified locations Grid-aligned positions Coverage with “holes” Repeated positions Inaccurate feature classes Places outside their assigned country Near-identical places
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Example: ‘Simplified’ Locations
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Grid positions: Lofoten
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Example: Nordfjord
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Magnitude of error
Dependent on latitude
Distortion or error may influence calculations
Manually edited points may have better positional accuracy
Solution: error annotation?
NIK 2015[Assessment of the Accuracy of GeoNames Gazetteer
Data, GIR2013]
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Separating on/off grid
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Intrinsic Quality Indicators
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POIs
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Population numbers
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Conclusion Set of intrinsic indicators
Highlighting of problematic areas Selection according to
requirements Impact depends on granularity
requirements of application Varying quality levels Dependencies differ from
mainland Future work
Provenance data not available, comparison with Web sources
World scale
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