1. U.S. Department of the Interior U.S. Geological Survey A Consideration of Geospatial Feature Formation in Linked Open Vocabularies Workshop on Linked Open Data: Activities, Ideas, Practices @ GIForum 2014 Dalia Varanka July 1, 2014

2. Geospatial Feature ISO 19112 Geographic Information – Spatial referencing by geographic identifiers OGC 11-052r4 OGC GeoSPARQL – A Geographic Query Language for RDF Data geo:Feature geo:Geometry geo:hasGeometry

3. Definitions  Abstraction of real world phenomena (ISO)  A digital representation of a real world entity or an abstraction of the real world (OGC) Selection of characteristics relevant to an area of interest with disregard of what is irrelevant

4. Introduction  Concept of a geospatial feature in GIScience literature  Feature class semantics in Linked Open Vocabulary (LOV)  Feature as ontology pattern  Hydrography example

5. Geographical and Cognitive Entities  Features are conceptualized as objects  World has fuzzy boundaries  Cognitively constructed categories  Technical adaptation of the feature concept  Imposes further semantic constraints  Must support geographical analysis

6. Geospatial Feature Concept Theme Space Time Equivalent to a ‘geographical fact’ Berry, B.J.L. 1964. Approaches to Spatial Analysis: A Regional Synthesis. Annals of the Association of American Geographers, 54, 2-11.

7. Feature Type Class Semantics Identity Place (Space) Time Attributes Relations Usery, E.L., Spatial Feature classes, Encyclopedia of Geography, John Wiley and Sons, In press.

8. GeoNames Feature Classes (9) and Code Definitions (645)

9. Geonames Feature Class Semantics feature class feature codegeonameidnameasciinamelatitudelongitudecountry codetimezonemodification date TPASS2598245Sandgatterl 47.7514.56667ATEurope/Vienna5/2/2014 LGRAZ2598246Viehtalalm 47.7514.56667ATEurope/Vienna4/30/1999 TCLF2598247Adlmoarstein 47.7514.55ATEurope/Vienna4/30/1999 LGRAZ2598248Waldbaueralm 47.7514.56667ATEurope/Vienna4/30/1999 TPK2598249Federeck 47.7514.56667ATEurope/Vienna5/2/2014 PPPL2598250MooshöheMooshoehe47.7514.55ATEurope/Vienna5/2/2014 SHUT2598251AntonihütteAntonihuette47.7514.53333ATEurope/Vienna5/2/2014 LGRAZ2598252Bergeralm 47.7514.51667ATEurope/Vienna4/30/1999 LGRAZ2598253Blabergalm 47.7514.5ATEurope/Vienna4/30/1999

10. Feature Semantics in Layer-Based Geographic Information Systems (GIS)  Improved attribute and topological representation  Feature class changed from type to geometry  Feature geometry changed from objects to tabular coordinate pair segments  Feature geometry classes: effective for overlay processing, but not intuitive for feature recognition

11. Feature Semantics Remedied in Cartography  Rich spatial, thematic, and temporal representation  Web Feature Service (WFS): syntax, but not semantics

12. Web Ontology Language (OWL)  Hierarchical Class  Defined Class Spatial relationship of features that cross but do not exchange flow Subclass of SpatialQuality Equivalent to crosses min 2 Object Disjoint with HydroNetJunction Domain of PermenantIdentifier Domain of AbovePermenantIdentifier Domain of BelowPermenantIdentifier

13. Feature Pattern Semantics  Identity  typeOf  Attribute  equivalentTo  Spatial Reference  hasGeometry  Temporal Reference  Spatial Relations  GeoSPARQL

14. LOV for U.S. National Hydrography Dataset (NHD)

15. GIS-NHD Triples From Tables Subject Property Literal Object

16. Domain Classes Allowable subjects of a property are limited to a particular table NHDVerticalRelationship String Above_Permanent_Identifier

17. Surface Water Ontology NHD Feature Ontology Instance Gazetteer Ontology Mapping and Display Database Maintenance Provenance and Metadata Cognitive Recognition Applied Model Database

18. NHD Instance (Gazetteer) Classes Instance Gazetteer Name Geometry & Spatial Qualities Permanent Identifier Hydro_Net Processes Hydro_Net Junction Flow Direction From Permanent Identifier To Permanent Identifier Point Line Area Elevation Vertical Relationship Relationship to Surface Above Permanent Identifier Below Permanent Identifier HU Code TNM ID

19. Semantic Enhancements: Transitivity Extensions to segments support inference

20. Conclusion  Geospatial feature type class semantics worth maintaining in LOV  Feature class modeled as a pattern in LOV  LOV object properties support LOD datatype properties