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, GIForum 2014 Dalia Varanka July 1, 2014

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

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

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

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

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

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.

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

Geonames Feature Class Semantics feature class feature codegeonameidnameasciinamelatitudelongitudecountry codetimezonemodification date TPASS Sandgatterl ATEurope/Vienna5/2/2014 LGRAZ Viehtalalm ATEurope/Vienna4/30/1999 TCLF Adlmoarstein ATEurope/Vienna4/30/1999 LGRAZ Waldbaueralm ATEurope/Vienna4/30/1999 TPK Federeck ATEurope/Vienna5/2/2014 PPPL MooshöheMooshoehe ATEurope/Vienna5/2/2014 SHUT AntonihütteAntonihuette ATEurope/Vienna5/2/2014 LGRAZ Bergeralm ATEurope/Vienna4/30/1999 LGRAZ Blabergalm ATEurope/Vienna4/30/1999

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

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

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

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

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

GIS-NHD Triples From Tables Subject Property Literal Object

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

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

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

Semantic Enhancements: Transitivity Extensions to segments support inference

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