RDF generation

This page describes how ToposKG converts input data into RDF triples.

Overview

The RDF generation process takes normalized geospatial entities and serializes them as RDF resources. Each generated entity may include:

a URI
one or more RDF types
labels or names
source attributes
geometry information
links to related entities

Basic RDF structure

A generated entity may look like this in Turtle:

@prefix topos: <https://example.org/toposkg/ontology/> .
@prefix geo: <http://www.opengis.net/ont/geosparql#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .

<https://example.org/toposkg/resource/waterbody/12345>
    a topos:Waterbody ;
    rdfs:label "Example Lake"@en ;
    geo:hasGeometry <https://example.org/toposkg/resource/geometry/12345> .

<https://example.org/toposkg/resource/geometry/12345>
    a geo:Geometry ;
    geo:asWKT "POINT(23.72 37.98)"^^geo:wktLiteral .

Entity triples

For each input entity, ToposKG should generate core triples such as:

entity-uri rdf:type class-uri
entity-uri rdfs:label label-literal
entity-uri geo:hasGeometry geometry-uri

Additional triples may be generated depending on the available input attributes.

Geometry triples

Geometry triples represent spatial information using GeoSPARQL-compatible properties.

Typical structure:

entity-uri geo:hasGeometry geometry-uri
geometry-uri geo:asWKT wkt-literal

Supported geometry types may include:

Point
LineString
Polygon
MultiPolygon

Attribute mapping

Input attributes can be mapped to RDF predicates.

Example input attribute:

population=10000

Example RDF output:

<https://example.org/toposkg/resource/admin/1>
    topos:population "10000"^^<http://www.w3.org/2001/XMLSchema#integer> .

Output formats

ToposKG may support multiple RDF serialization formats.

Format	Extension	Description
N-Triples	`.nt`	Simple line-based RDF serialization. Useful for large files.
Turtle	`.ttl`	Under construction
RDF/XML	`.rdf`	Under construction