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The National Map

Home ← Geospatial Semantics and Ontology

Geospatial Semantics and Ontology

The goal of the project "Building Ontology for The National Map" is to specify geospatial feature semantics for richer data models. New data models and associated knowledge organization systems for The National Map can translate traditional topographic information into a flexible spatiotemporal knowledge base that can serve many different application areas.


A USGS Open-File Report, titled "Introduction to Geospatial Semantics and Technology Workshop Handbook", is an introductory tutorial on geospatial semantics with hands-on exercises using standard Web browsers. The workshop is divided into two major sections: general semantics on the Web, and specific examples of geospatial semantics using data from The National Map of the USGS. Additional resources are included.

Constructing Ontologies from The National Map Triples

Guide for Creating and Using National Map RDF Data

Data downloaded from The National Map can be converted into RDF triples by following the steps outlined here.

USGS Created Ontologies

  • GIS NHD is a simple ontology directly compiled using the conversion program linked from “Guide for Creating and Using National Map RDF Data.” NHD attribute headings take the form of object and datatype properties. Table names serve as domain and range classes for properties.
  • This surface water ontology (SWO) is based on GIS NHD, but organized using the Basic Formal Ontology (BFO) and modified for semantic technology conventions.
  • USTopographic is a simple ontology formed to connect separate semantic modules for The National Map.

The Topographic Feature Vocabularies

A controlled vocabulary provides a way to specify triple data semantics. Formal specifications provide a cohesive basis for a topographic feature type vocabulary for triple data. The feature list is based on standards for the various themes of The National Map, the Digital Line Graph (DLG) feature list derived from field-surveyed 20th-century maps, the Geographic Names Information System (GNIS), and the Spatial Data Transfer Standard (SDTS).

(The files are in Terse RDF Triple Language (Turtle), which uses the file extension .ttl. )



Built Up Areas

Ecological Regimes

Surface Water


The vocabulary is not meant to be a comprehensive inventory of all available scientific terms. The terms were selected for the original standards based on whether the USGS would produce digital data for those feature types or whether they are recognized in other data sets. The feature list vocabularies will continue to be reviewed and updated.

SPARQL Endpoint and Sample Data

Selected data sets from The National Map are now available in the data model of the Semantic Web, Resource Description Framework (RDF) triples. These triples can be downloaded and used as linked data for Web 2.0 and Web 3.0 applications. A SPARQL endpoint is available for querying and saving subsets of the data.

More Information

Papers and Posters

A collection of publications, posters, and reports are available for specific information about geospatial semantics and ontology.

Abstracts, Presentations and Activities

Our involvement in related events, presentations, and abstracts are included here.

Virtual Communities

Project Team

Dalia Varanka, Project Lead

E. Lynn Usery

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Last modified: Tuesday, 09-Dec-2014 15:13:16 EST