6.2.1  SpatialObject

The class SpatialObject is defined by the following:

geo:SpatialObject
    a rdfs:Class, owl:Class ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "Spatial Object"@en ;
    skos:definition "Anything spatial (being or having a shape, position or an extent)."@en ;
    skos:note "Subclasses of this class are expected to be used for instance data."@en ;
.

Example:

eg:x
    a geo:SpatialObject ;
     skos:prefLabel "Object X";
.

6.2.2  Feature

The class Feature is equivalent to the class GFI_Feature ISO 19156 and is defined by the following:

geo:Feature
    a rdfs:Class, owl:Class ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "Feature"@en ;
    rdfs:subClassOf geo:SpatialObject ;
    owl:disjointWith geo:Geometry ;
    skos:definition "A discrete spatial phenomenon in a universe of discourse."@en ;
    skos:note "A Feature represents a uniquely identifiable phenomenon, for example
              a river or an apple. While such phenomena (and therefore the Features
              used to represent them) are bounded, their boundaries may be crisp
              (e.g., the declared boundaries of a state), vague (e.g., the
              delineation of a valley versus its neighboring mountains), and change
              with time (e.g., a storm front). While discrete in nature, Features
              may be created from continuous observations, such as an isochrone
              that determines the region that can be reached by ambulance within
              5 minutes."@en ;
.

6.2.3  SpatialObjectCollection

The class SpatialObjectCollection is defined by the following:

geo:SpatialObjectCollection
    a owl:Class ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "Spatial Object Collection" ;
    skos:definition "A collection of individual Spatial Objects."@en ;
    skos:note "This is the superclass of Feature Collection and Geometry Collection."@en ;
    rdfs:subClassOf rdfs:Container ;
    rdfs:subClassOf [
        a owl:Restriction ;
        owl:allValuesFrom geo:SpatialObject ;
        owl:onProperty rdfs:member ;
    ] ;
.

Membership of the generic rdfs:Container that defines this class is restricted to instances of SpatialObject. SpatialObjectCollection members are to be indicated with the rdfs:member property.

6.2.4  FeatureCollection

The class FeatureCollection is defined by the following:

geo:FeatureCollection
    a owl:Class ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "Feature Collection" ;
    skos:definition "A collection of individual Features."@en ;
    rdfs:subClassOf geo:SpatialObjectCollection ;
    rdfs:subClassOf [
        a owl:Restriction ;
        owl:allValuesFrom :Feature ;
        owl:onProperty rdfs:member ;
    ] ;
.

Membership of the more general SpatialObjectCollection that defines this class is restricted to instances of Feature. FeatureCollection members are to be indicated with the rdfs:member property.

6.3.1  hasSize

The property hasSize is the superproperty of all properties that can be used to indicate the size of a Spatial Object in case (only) metric units (meter, square meter or cubic meter) cannot be used. If it is possible to express size in metric units, subproperties of hasMetricSize should be used. This property has no range specification. This makes it possible to use other vocabularies for expressions of size, for example, vocabularies for units of measurement or vocabularies for specifying measurement quality.

GeoSPARQL 1.1 defines the following subproperties of this property: hasLength, hasPerimeterLength, hasArea and hasVolume.

geo:hasSize
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:domain geo:SpatialObject ;
	skos:definition "Subproperties of this property are used to indicate the size of a
                    Spatial Object as a measurement or estimate of one or more dimensions
                    of the Spatial Object's spatial presence."@en ;
	skos:prefLabel "has size"@en ;
.

6.3.2  hasMetricSize

The property hasMetricSize is the superproperty of all properties that can be used to indicate the size of a Spatial Object using metric units (meter, square meter or cubic meter). Using a subproperty of this property is the recommended way to specify size, because using a standard unit of length (meter) benefits data interoperability and simplicity. Subproperties of hasSize can be used if more complex expressions are necessary, for example, if the unit of length cannot be converted to meter, or if additional data are needed to describe the measurement or estimate of size.

GeoSPARQL 1.1 defines the following subproperties of this property: hasMetricLength, hasMetricPerimeterLength, hasMetricArea and hasMetricVolume.

geo:hasMetricSize
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:domain geo:SpatialObject ;
	rdfs:range xsd:double ;
	skos:definition "Subproperties of this property are used to indicate the size of a
                    Spatial Object, as a measurement or estimate of one or more dimensions
                    of the Spatial Object's spatial presence. Units are always metric
                    (meter, square meter or cubic meter)."@en ;
	skos:prefLabel "has metric size"@en ;
.

6.3.3  hasLength

The property hasLength can be used to indicate the length of a Spatial Object if it is not possible to use the property hasMetricLength. It is a subproperty of hasSize.

geo:hasLength
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:subPropertyOf geo:hasSize ;
	rdfs:domain geo:SpatialObject ;
	skos:definition "The length of a Spatial Object."@en ;
	skos:prefLabel "has length"@en ;
.

6.3.4  hasMetricLength

The property hasMetricLength can be used to indicate the length of a Spatial Object in meters (m). It is a subproperty of hasMetricSize. This property can be used for Spatial Objects having one, two, or three dimensions.

geo:hasMetricLength
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:subPropertyOf geo:hasMetricSize ;
	rdfs:domain geo:SpatialObject ;
	rdfs:range xsd:double ;
	skos:definition "The length of a Spatial Object in meters."@en ;
	skos:prefLabel "has length in meters"@en ;
.

6.3.5  hasPerimeterLength

The property hasPerimeterLength can be used to indicate the length of the outer boundary of a Spatial Object if it is not possible to use the property hasMetricPerimeterLength. It is a subproperty of hasSize.

geo:hasPerimeterLength
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:subPropertyOf geo:hasSize ;
	skos:definition "The length of the perimeter of a Spatial Object."@en ;
	skos:prefLabel "has perimeter length"@en ;
.

6.3.6  hasMetricPerimeterLength

The property hasMetricPerimeterLength can be used to indicate the length of the outer boundary of a Spatial Object in meters (m). It is a subproperty of hasMetricSize. Circumference is considered a type of perimeter, so this property can be used for circular or curved objects too. This property can be used for Spatial Objects having two or three dimensions.

geo:hasMetricPerimeterLength
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:subPropertyOf geo:hasMetricSize ;
	rdfs:domain geo:SpatialObject ;
	rdfs:range xsd:double ;
	skos:definition "The length of the perimeter of a Spatial Object in meters."@en ;
	skos:prefLabel "has perimeter length in meters"@en ;
.

    PREFIX geo: <http://www.opengis.net/ont/geosparql#>
    ASK
    WHERE {
        ?g geo:hasMetricPerimeterLength ?p ;
           geo:dimension ?d .

        FILTER (?d < 2)
    }

6.3.7  hasArea

The property hasArea can be used to indicate the area of a Spatial Object if it is not possible to use the property hasMetricArea. It is a subproperty of hasSize.

geo:hasArea
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:subPropertyOf geo:hasSize ;
	rdfs:domain geo:SpatialObject ;
	skos:definition "The area of a Spatial Object."@en ;
	skos:prefLabel "has area"@en ;
.

6.3.8  hasMetricArea

The property hasMetricArea can be used to indicate the area of a Spatial Object in square meters (m²). It is a subproperty of hasMetricSize. This property can be used for Spatial Objects having two or three dimensions.

geo:hasMetricArea
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:subPropertyOf geo:hasMetricSize ;
	rdfs:domain geo:SpatialObject ;
	rdfs:range xsd:double ;
	skos:definition "The area of a Spatial Object in square meters."@en ;
	skos:prefLabel "has area in meters"@en ;
.

    PREFIX geo: <http://www.opengis.net/ont/geosparql#>

    ASK
    WHERE {
        ?g geo:hasMetricArea ?a ;
           geo:dimension ?d .

        FILTER (?d < 2)
    }

6.3.9  hasVolume

The property hasVolume can be used to indicate the volume of a Spatial Object if it is not possible to use the property hasMetricVolume. It is a subproperty of hasSize.

geo:hasVolume
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:subPropertyOf geo:hasSize ;
	rdfs:domain geo:SpatialObject ;
	skos:definition "The volume of a three-dimensional Spatial Object."@en ;
	skos:prefLabel "has volume"@en ;
.

6.3.10  hasMetricVolume

The property hasMetricVolume can be used to indicate the volume of a Spatial Object in cubic meters (m³). It is a subproperty of hasMetricSize. This property can be used for Spatial Objects having three dimensions.

geo:hasMetricVolume
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
	rdfs:subPropertyOf :hasMetricSize ;
	rdfs:domain geo:SpatialObject ;
	rdfs:range xsd:double ;
	skos:definition "The volume of a Spatial Object in cubic meters."@en ;
	skos:prefLabel "has area in meters"@en ;
.

    PREFIX geo: <http://www.opengis.net/ont/geosparql#>

    ASK
    WHERE {
        ?g geo:hasMetricVolume ?v ;
           geo:dimension ?d .

        FILTER (?d != 3)
    }

6.4.1  hasGeometry

The property hasGeometry is used to link a Feature with a Geometry that represents its spatial extent. A given Feature may have many associated geometries.

geo:hasGeometry
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
    rdfs:domain geo:Feature ;
    rdfs:range geo:Geometry ;
    skos:prefLabel "has Geometry"@en ;
    skos:definition "A spatial representation for a given Feature."@en ;
.

6.4.2  hasDefaultGeometry

The property hasDefaultGeometry is used to link a Feature with its default Geometry. The default geometry is the Geometry that should be used for spatial calculations in the absence of a request for a specific geometry (e.g. in the case of query rewrite).

geo:hasDefaultGeometry
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
    rdfs:domain geo:Feature ;
    rdfs:range geo:Geometry ;
    skos:prefLabel "has Default Geometry"@en ;
    skos:definition "The default geometry to be used in spatial calculations,
                    usually the most detailed geometry."@en ;
    rdfs:subPropertyOf geo:hasGeometry ;
.

GeoSPARQL does not restrict the cardinality of the has default geometry property. It is thus possible for a Feature to have more than one distinct default geometry or to have no default geometry. This situation does not result in a query processing error; SPARQL graph pattern matching simply proceeds as normal. Certain queries may, however, give logically inconsistent results. For example, if a Feature my:f1 has two asserted default geometries, and those two geometries are disjoint polygons, the query below could return a non-zero count on a system supporting the GeoSPARQL Query Rewrite Extension (rule geor:sfDisjoint).

PREFIX geo: <http://www.opengis.net/ont/geosparql#>

SELECT (COUNT(*) AS ?cnt)
WHERE { :f1 geo:sfDisjoint :f1 }

Such cases are application-specific data modeling errors and are therefore outside of the scope of the GeoSPARQL specification. However, it is recommended that multiple geometries indicated with hasDefaultGeometry should be differentiated by Geometry class properties, perhaps relating to precision, SRS etc.

6.4.3  hasBoundingBox

The property hasBoundingBox is used to link a Feature with a simplified geometry-representation corresponding to the envelope of its geometry. Bounding-boxes are typically used in indexing and discovery.

geo:hasBoundingBox
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
    rdfs:subPropertyOf geo:hasGeometry ;
    rdfs:domain geo:Feature ;
    rdfs:range geo:Geometry ;
    skos:prefLabel "has bounding box"@en ;
    skos:definition "The minimum or smallest bounding or enclosing box of a given Feature."@en ;
    skos:scopeNote "The target is a geometry that defines a rectilinear region whose edges are
                    aligned with the axes of the coordinate reference system, which exactly
                    contains the geometry or Feature e.g. sf:Envelope"@en ;
.

GeoSPARQL does not restrict the cardinality of the hasBoundingBox property. A Feature may be associated with more than one bounding-box, for example in different coordinate reference systems.

6.4.4  hasCentroid

The property hasCentroid is used to link a Feature with a point geometry corresponding with the centroid of its geometry. The centroid is typically used to show location on a low-resolution image, and for some indexing and discovery functions.

geo:hasCentroid
    a rdf:Property, owl:ObjectProperty ;
    rdfs:isDefinedBy geo: ;
    rdfs:subPropertyOf geo:hasGeometry ;
    rdfs:domain geo:Feature ;
    rdfs:range geo:Geometry ;
    skos:prefLabel "has centroid"@en ;
    skos:definition "The arithmetic mean position of all the geometry points
                    of a given Feature."@en ;
    skos:scopeNote "The target geometry shall describe a point, e.g. sf:Point"@en ;
.

GeoSPARQL does not restrict the cardinality of the hasCentroid property. A Feature may be associated with more than one centroid, for example computed using different rules or in different coordinate reference systems.

8.6.1  Geometry

The class Geometry is conceptually derived from UML class Geometry in ISO 19107 which is that standard’s “root class of the geometric object taxonomy and supports interfaces common to all geographically referenced geometric objects”. Geometry is defined by the following:

geo:Geometry
    a rdfs:Class, owl:Class ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "Geometry"@en ;
    rdfs:subClassOf geo:SpatialObject ;
    owl:disjointWith geo:Feature;
    skos:definition "A coherent set of direct positions in space. The positions
                    are held within a Spatial Reference System (SRS)."@en ;
    skos:note "Geometry can be used as a representation of the shape, extent or
              location of a Feature and may exist as a self-contained entity."@en ;
.

8.6.2  Geometry Collection

The class GeometryCollection is defined by the following:

geo:GeometryCollection
  a owl:Class ;
  rdfs:isDefinedBy geo: ;
  skos:prefLabel "Geometry Collection"@en ;
  skos:definition "A collection of individual Geometries."@en ;
  rdfs:subClassOf geo:SpatialObjectCollection ;
  rdfs:subClassOf [
      a owl:Restriction ;
      owl:allValuesFrom geo:Geometry ;
      owl:onProperty rdfs:member ;
    ] ;
.

Membership of the general SpatialObjectCollection that defines this class is restricted to instances of Geometry. GeometryCollection members are to be indicated with the rdfs:member property.

8.7.1  dimension

The property dimension is used to link a Geometry object to its topological dimension, which must be less than or equal to the coordinate dimension. In non-homogeneous collections, this will return the largest topological dimension of the contained objects.

geo:dimension
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "dimension"@en ;
    skos:definition "The topological dimension of this geometric object, which
                    must be less than or equal to the coordinate dimension. In
                    non-homogeneous collections, this is the largest
                    topological dimension of the contained objects."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range xsd:integer ;
.

8.7.2  coordinateDimension

The property coordinateDimension is defined to link a Geometry object to the dimension of direct positions (coordinate tuples) used in the Geometry’s definition.

geo:coordinateDimension
    a rdf:Property, owl:DatatypeProperty;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "coordinate dimension"@en ;
    skos:definition "The number of measurements or axes needed to describe the
                    position of this Geometry in a coordinate system."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range xsd:integer ;
.

8.7.3  hasSpatialDimension

The property hasSpatialDimension is defined to link a Geometry object to the dimension of the spatial portion of the direct positions (coordinate tuples) used in its serializations. If the direct positions do not carry a measure coordinate, this will be equal to the coordinate dimension.

geo:hasSpatialDimension
    a rdf:Property, owl:DatatypeProperty;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "spatial dimension"@en ;
    skos:definition "The number of measurements or axes needed to describe the
                    spatial position of this Geometry in a coordinate system."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range xsd:integer ;
.

8.7.4  hasSpatialResolution

The property hasSpatialResolution is defined to indicate the spatial resolution of the elements within a Geometry. Spatial resolution specifies the level of detail of a Geometry. It is the smallest distinguishable distance between adjacent coordinate sets. This property is not applicable to a point Geometry, because a point consists of a single coordinate set.

Since this property is defined for a Geometry, all literal representations of that Geometry instance must have the same spatial resolution.

geo:hasSpatialResolution
    a rdf:Property, owl:ObjectProperty;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "has spatial resolution"@en ;
    skos:definition "The spatial resolution of a Geometry"@en ;
    rdfs:domain geo:Geometry ;
.

8.7.5  hasMetricSpatialResolution

The property hasMetricSpatialResolution is similar to hasSpatialResolution, except that the unit of resolution is always meter (the standard distance unit of the International System of Units).

geo:hasMetricSpatialResolution
    a rdf:Property, owl:ObjectProperty;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "has spatial resolution in meters"@en ;
    skos:definition "The spatial resolution of a Geometry in meters."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range xsd:double ;
.

8.7.6  hasSpatialAccuracy

The property hasSpatialAccuracy is applicable when a Geometry is used to represent a Feature. It is expressed as a distance that indicates the truthfulness of the positions (coordinates) that define the Geometry. In this case accuracy defines a zone surrounding each coordinate within which the real positions are known to be. The accuracy value defines this zone as a distance from the coordinate(s) in all directions (e.g. a line, a circle or a sphere, depending on spatial dimension).

geo:hasSpatialAccuracy
    a rdf:Property, owl:ObjectProperty;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "has spatial accuracy"@en ;
    skos:definition "The positional accuracy of the coordinates of a Geometry."@en ;
    rdfs:domain geo:Geometry ;
.

8.7.7  hasMetricSpatialAccuracy

The property hasMetricSpatialAccuracy is similar to has spatial accuracy, but is easier to specify and use because the unit of distance is always meter (the standard distance unit of the International System of Units).

geo:hasMetricSpatialAccuracy
    a rdf:Property, owl:ObjectProperty;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "has spatial accuracy in meters"@en ;
    skos:definition "The positional accuracy of the coordinates of a Geometry in meters."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range xsd:double ;
.

8.7.8  isEmpty

The property isEmpty will indicate a Boolean object set to true if and only if the Geometry contains no information.

geo:isEmpty
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "is empty"@en ;
    skos:definition "(true) if this geometric object is the empty Geometry. If
                    true, then this geometric object represents the empty point
                    set for the coordinate space."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range xsd:boolean ;
.

8.7.9  isSimple

The property isSimple will indicate a Boolean object set to true if and only if the Geometry contains no self-intersections, with the possible exception of its boundary.

geo:isSimple
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "is simple"@en ;
    skos:definition "(true) if this geometric object has no anomalous geometric
                    points, such as self intersection or self tangency."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range xsd:boolean ;
.

8.7.10  hasSerialization

The property hasSerialization is defined to connect a Geometry with its text-based serialization (e.g., its WKT serialization).

geo:hasSerialization
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "has serialization"@en ;
    skos:definition "Connects a Geometry object with its text-based serialization."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range rdfs:Literal ;
.

8.8.1  Well-Known Text

This section establishes the requirements for representing Geometry data in RDF based on Well-Known Text (WKT) as defined by Simple Features Access OGC 06-103r4 ISO 19125-1. It defines one RDFS Datatype: WKT Literal and one property, as WKT.

geo:wktLiteral
    a rdfs:Datatype ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "Well-known Text literal"@en ;
    skos:definition "A Well-known Text serialization of a Geometry object."@en ;
.

wktLiteral ::= opt-iri-and-whitespace geometry-data

opt-iri-and-space = "<" IRI ">" LWSP / ""

"Point(-83.38 33.95)"^^<http://www.opengis.net/ont/geosparql#wktLiteral>

"<http://www.opengis.net/def/crs/EPSG/0/4326> Point(33.95 -83.38)"^^<http://www.opengis.net/ont/geosparql#wktLiteral>

geo:asWKT
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:subPropertyOf geo:hasSerialization ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "as WKT"@en ;
    skos:definition "The WKT serialization of a Geometry."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range geo:wktLiteral ;
.

geof:asWKT (geom: ogc:geomLiteral): geo:wktLiteral

8.8.2  Geography Markup Language

This section establishes a Requirements class for representing Geometry data in RDF based on GML as defined by the Geography Markup Language Encoding Standard OGC 07-036. It defines one RDFS Datatype: GML Literal and one property, as GML.

geo:gmlLiteral
    a rdfs:Datatype ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "GML literal"@en ;
    skos:definition "The datatype of GML literal values"@en ;
.

"""
<gml:Point
        srsName=\"http://www.opengis.net/def/crs/OGC/1.3/CRS84\"
        xmlns:gml=\"http://www.opengis.net/gml/3.2\">
    <gml:pos>-83.38 33.95</gml:pos>
</gml:Point>
"""^^<http://www.opengis.net/ont/geosparql#gmlLiteral>

geo:asGML
    a rdf:Property ;
    rdfs:subPropertyOf geo:hasSerialization ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "as GML"@en ;
    skos:definition "The GML serialization of a Geometry."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range geo:gmlLiteral ;
.

geof:asGML (geom: ogc:geomLiteral, gmlProfile: xsd:string): geo:gmlLiteral

8.8.3  GeoJSON

This section establishes a Requirements class for representing Geometry data in RDF based on Geographic JavaScript Object Notation (GeoJSON) as defined by [GeoJSON]. It defines one RDFS Datatype: geoJsonLiteral and one property, as GeoJSON.

geo:geoJSONLiteral a rdfs:Datatype ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "GeoJSON Literal"@en ;
    skos:definition "A GeoJSON serialization of a Geometry object."@en .

"""
{"type": "Point", "coordinates": [-83.38,33.95]}
"""^^<http://www.opengis.net/ont/geosparql#geoJSONLiteral>

geo:asGeoJSON
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:subPropertyOf geo:hasSerialization ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "as GeoJSON"@en ;
    skos:definition "The GeoJSON serialization of a Geometry."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range geo:geoJSONLiteral ;
.

geof:asGeoJSON (geom: ogc:geomLiteral): geo:geoJSONLiteral

8.8.4  Keyhole Markup Language

This section establishes the Requirements class for representing Geometry data in RDF based on KML as defined by OGC 12-007r2. It defines one RDFS Datatype: KML Literal and one property, asKML.

geo:kmlLiteral
    a rdfs:Datatype ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "KML Literal"@en ;
    skos:definition "A KML serialization of a Geometry object."@en ;
.

"""
<Point xmlns=\"http://www.opengis.net/kml/2.2\">
    <coordinates>-83.38,33.95</coordinates>
</Point>
"""^^<http://www.opengis.net/ont/geosparql#kmlLiteral>

geo:asKML
    a rdf:Property, owl:DatatypeProperty;
    rdfs:subPropertyOf geo:hasSerialization ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "as KML"@en ;
    skos:definition "The KML serialization of a Geometry."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range geo:kmlLiteral ;
.

geof:asKML (geom: ogc:geomLiteral): geo:kmlLiteral

8.8.5  Discrete Global Grid System

This section establishes the Requirements class for representing Discrete Global Grid System (DGGS) Geometry data as RDF literals. The form of geometry data representation is specific to individual DGGS implementations: known DGGSes are not compatible or even very similar.

The Requirements class defines one RDFS Datatype and one property, .

geo:dggsLiteral
    a rdfs:Datatype ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "DGGS Literal"@en ;
    skos:definition "A textual serialization of a Discrete Global Grid System (DGGS) Geometry object."@en
.

dggsLiteral ::= iri-and-whitespace dggs-geomety-data

iri-and-whitespace = "<" IRI ">" LWSP

"<https://w3id.org/dggs/auspix> CELL (R3234)"^^geo:dggsLiteral

dggsLiteral ::= iri-and-space dggs-geometry-data

iri-and-whitespace = "<" IRI ">" LWSP / ""

geo:asDGGS
    a rdf:Property, owl:DatatypeProperty ;
    rdfs:subPropertyOf geo:hasSerialization ;
    rdfs:isDefinedBy geo: ;
    skos:prefLabel "as DGGS"@en ;
    skos:definition "A DGGS serialization of a Geometry."@en ;
    rdfs:domain geo:Geometry ;
    rdfs:range geo:dggsLiteral ;
.

geof:asDGGS (geom: ogc:geomLiteral, specificDggsDatatype: xsd:anyURI): geo:DggsLiteral

8.9.1  Function notes

These notes apply to all the following functions in this section.

An invocation of any the following functions with invalid arguments produces an error. An invalid argument includes any of the following:

A more detailed description of expected inputs and expected outputs of the given functions is shown in Annex B.

Unless otherwise stated in the function definition, the following behaviors should be followed by all SPARQL extension functions defined in the GeoSPARQL standard:

For further discussion of the effects of errors during FILTER evaluation, consult Section 17⁹⁾ of the SPARQL specification W3C sparql11-query.

Note that returning values instead of raising an error serves as an extension mechanism of SPARQL.

From Section 17.3.1¹⁰⁾ of the SPARQL specification W3C sparql11-query:

This extension mechanism enables GeoSPARQL implementations to simultaneously support multiple geometry serializations. For example, a system that supports WKT Literal serializations may also support GML Literal serializations and consequently would not raise an error if it encounters multiple geometry datatypes while processing a given query.

8.9.2  metricArea

geof:metricArea (geom: ogc:geomLiteral): xsd:double

The function geof:metricArea returns the area of geom in square meters. Must return zero for all geometry types other than Polygon. This function is similar to area but does not need a specification of measurement unit.

8.9.3  area

geof:area (geom: ogc:geomLiteral, units: rdfs:Resource): xsd:double

The function geof:area returns the area of geom. Must return zero for all geometry types other than Polygon. This function is similar to metricArea, which does not need a specification of measurement unit.

8.9.4  boundary

geof:boundary (geom: ogc:geomLiteral): ogc:geomLiteral

The function geof:boundary returns the closure of the boundary of geom. Calculations are in the spatial reference system of geom.

8.9.5  boundingCircle

geof:boundingCircle (geom: ogc:geomLiteral): ogc:geomLiteral

The function geof:boundingCircle returns the minimum bounding circle around geom. Calculations are in the spatial reference system of geom.

8.9.6  metricBuffer

geof:metricBuffer (geom: ogc:geomLiteral,
                   radius: xsd:double): ogc:geomLiteral

The function geof:metricBuffer returns a geometric object that represents all Points whose distance from geom is less than or equal to the radius measured in meters. Calculations are in the coordinate reference system of geom. This function is similar to buffer, but does not need a specification of measurement unit.

8.9.7  buffer

geof:buffer (geom: ogc:geomLiteral,
             radius: xsd:double,
             units: xsd:anyURI): ogc:geomLiteral

The function geof:buffer returns a geometric object that represents all Points whose distance from geom is less than or equal to the radius measured in units. Calculations are in the spatial reference system of geom. This function is similar to metricBuffer, which does not need a specification of measurement unit.

8.9.8  centroid

geof:centroid (geom: ogc:geomLiteral): ogc:geomLiteral

The function geof:centroid returns the mathematical centroid of geom. The centroid point does not have to be part of the surface it is derived from.

8.9.9  convexHull

geof:convexHull (geom: ogc:geomLiteral): ogc:geomLiteral

The function geof:convexHull returns a geometric object that represents all Points in the convex hull of geom. Calculations are in the spatial reference system of geom.

8.9.10  concaveHull

geof:concaveHull (geom: ogc:geomLiteral): ogc:geomLiteral

The function geof:concaveHull returns a geometric object that represents all Points in the concave hull of geom. Calculations are in the spatial reference system of geom. Various implementers use parameters to calculate a concave hull. As such, two implementations may return different results from their concave hull functions for the same geometry. Implementers should make clear any default values used to calculate a concave hull in their documentation.

8.9.11  coordinateDimension

geof:coordinateDimension (geom: ogc:geomLiteral): xsd:integer

The function geof:coordinateDimension returns the coordinate dimension of geom.

8.9.12  difference

geof:difference (geom1: ogc:geomLiteral,
                 geom2: ogc:geomLiteral): ogc:geomLiteral

The function geof:difference returns a geometric object that represents all Points in the set difference of geom1 with geom2. Calculations are in the spatial reference system of geom1.

8.9.13  dimension

geof:dimension (geom: ogc:geomLiteral): xsd:integer

The function geof:dimensions returns the dimension of geom. In non-homogeneous geometry collections, this will return the largest topological dimension of the contained objects.

8.9.14  metricDistance

geof:metricDistance (geom1: ogc:geomLiteral,
                     geom2: ogc:geomLiteral): xsd:double

The function geof:metricDistance returns the shortest distance in meters between any two Points in the two geometric objects. Calculations are in the coordinate reference system of geom1. This function is similar to distance, but does not need a specification of measurement unit.

8.9.15  distance

geof:distance (geom1: ogc:geomLiteral,
               geom2: ogc:geomLiteral,
               units: xsd:anyURI): xsd:double

The function geof:distance returns the shortest distance in units between any two Points in the two geometric objects. Calculations are in the spatial reference system of geom1. This function is similar to metricDistance, which does not need a specification of measurement unit.

8.9.16  envelope

geof:envelope (geom: ogc:geomLiteral): ogc:geomLiteral

The function geof:envelope returns the minimum bounding box — a rectangle — of geom. Calculations are in the spatial reference system of geom.

8.9.17  geometryN

geof:geometryN (geom: ogc:geomLiteral, geomindex: xsd:integer): ogc:geomLiteral

The function geof:geometryN returns the nth geometry of geom if it is a GeometryCollection that is defined in a literal type (such as in the case of a sf:GeometryCollection) or geom if it is a Geometry. This function is not applicable to the type geo:GeometryCollection, as elements in geo:GeometryCollection are not guaranteed to be ordered.

8.9.18  geometryType

geof:geometryType (geom: ogc:geomLiteral): xsd:anyURI

The function geof:geometryType returns the URI of the subtype of Geometry of which this geometric object is an member. No attempt to reconcile different geometry subtypes across all support literals need be made.

8.9.19  intersection

geof:intersection (geom1: ogc:geomLiteral,
                   geom2: ogc:geomLiteral): ogc:geomLiteral

The function geof:intersection returns a geometric object that represents all Points in the intersection of geom1 with geom2. Calculations are in the spatial reference system of geom1.

8.9.20  is3D

geof:is3D (geom: ogc:geomLiteral): xsd:boolean

The function geof:is3D Returns true if geom has z coordinate values. See [GeoSPARQL_and_Simple_Features__SFA-CA_] for a description of GeoSPARQL’s limitations: currently it supports 2.5D and geometric functions ignore Z values in calculations.

8.9.21  isEmpty

geof:isEmpty (geom: ogc:geomLiteral): xsd:boolean

The function geof:isEmpty returns true if geom is an empty geometry, i.e. contains no coordinates.

8.9.22  isMeasured

geof:isMeasured (geom: ogc:geomLiteral): xsd:boolean

The function geof:isMeasured returns true if geom has m coordinate values, as used e.g. in linear referencing. See [GeoSPARQL_and_Simple_Features__SFA-CA_] for a description of GeoSPARQL’s limitations: at the moment it does not support linear referencing and M values are ignored.

8.9.23  isSimple

geof:isSimple (geom: ogc:geomLiteral): xsd:boolean

The function geof:isSimple returns true if geom is a simple geometry, i.e. has no anomalous geometric points, such as self intersection or self tangency.

8.9.24  metricLength

geof:metricLength (geom: ogc:geomLiteral): xsd:double

The function geof:metricLength returns the length of geom in meters. The longest length from any one dimension is returned. This is for example the length of a line from its beginning point to its endpoint or the length of the boundary of a polygon. This function is similar to length but does not need a specification of measurement unit.

8.9.25  length

geof:length (geom: ogc:geomLiteral, units: rdfs:Resource): xsd:double

The function geof:length returns the length of geom. The longest length from any one dimension is returned. This function is similar to metricLength, which does not need a specification of measurement unit.

8.9.26  maxX

geof:maxX (geom: ogc:geomLiteral): xsd:double

The function geof:maxX returns the maximum X coordinate for geom using the SRS of geom.

8.9.27  maxY

geof:maxY (geom: ogc:geomLiteral): xsd:double

The function geof:maxY returns the maximum Y coordinate for geom using the SRS of geom.

8.9.28  maxZ

geof:maxZ (geom: ogc:geomLiteral): xsd:double

The function geof:maxZ returns the maximum Z coordinate for geom using the SRS of geom.

8.9.29  minX

geof:minX (geom: ogc:geomLiteral): xsd:double

The function geof:minX returns the minimum X coordinate for geom using the SRS of geom.

8.9.30  minY

geof:minY (geom: ogc:geomLiteral): xsd:double

The function geof:minY returns the minimum Y coordinate for geom using the SRS of geom.

8.9.31  minZ

geof:minZ (geom: ogc:geomLiteral): xsd:double

The function geof:minZ returns the minimum Z coordinate for geom using the SRS of geom.

8.9.32  numGeometries

geof:numGeometries (geom: ogc:geomLiteral): xsd:integer

The function geof:numGeometries returns the number of geometries of geom.

8.9.33  perimeter

geof:perimeter (geom: ogc:geomLiteral, unit: rdfs:Resource): xsd:double

The function geof:perimeter returns the perimeter of geom in the unit specified by the unit parameter for areal geometries. For non-areal geometries the result is equivalent to length.

8.9.34  metricPerimeter

geof:metricPerimeter (geom: ogc:geomLiteral): xsd:double

The function geof:metricPerimeter returns the perimeter of geom. It is similar to the function perimeter, but always returns the result in meters.

8.9.35  hasSpatialDimension

geof:hasSpatialDimension (geom: ogc:geomLiteral): xsd:integer

The function geof:hasSpatialDimension returns the spatial dimension of geom.

8.9.36  symDifference

geof:symDifference (geom1: ogc:geomLiteral,
                    geom2: ogc:geomLiteral): ogc:geomLiteral

The function geof:symDifference returns a geometric object that represents all Points in the set symmetric difference of geom1 with geom2. Calculations are in the spatial reference system of geom1.

8.9.37  transform

geof:transform (geom: ogc:geomLiteral, srsIRI: xsd:anyURI): ogc:geomLiteral

The function geof:transform converts geom to a spatial reference system defined by srsIRI. The function raises an error if a transformation is not mathematically possible.

8.9.38  union

geof:union (geom1: ogc:geomLiteral,
            geom2: ogc:geomLiteral): ogc:geomLiteral

This function geof:union returns a geometric object that represents all Points in the union of geom1 with geom2. Calculations are in the spatial reference system of geom1.

8.9.39  getSRID

geof:getSRID (geom: ogc:geomLiteral): xsd:anyURI

The function getSRID returns the spatial reference system IRI for geom.

8.10.1  aggBoundingBox

geof:aggBoundingBox (geom: ogc:geomLiteral): ogc:geomLiteral

The function aggBoundingBox calculates a minimum bounding box — rectangle — of the set of given geometries.

8.10.2  aggBoundingCircle

geof:aggBoundingCircle (geom: ogc:geomLiteral): ogc:geomLiteral

The function aggBoundingCircle calculates a minimum bounding circle of the set of given geometries.

8.10.3  aggCentroid

geof:aggCentroid (geom: ogc:geomLiteral): ogc:geomLiteral

The function aggCentroid calculates the centroid of the set of given geometries.

8.10.4  aggConcaveHull

geof:aggConcaveHull (geom: ogc:geomLiteral, targetPercent: xsd:double): ogc:geomLiteral

The function geof:aggConcaveHull calculates the concave hull of the set of given geometries.

8.10.5  aggConvexHull

geof:aggConvexHull (geom: ogc:geomLiteral): ogc:geomLiteral

The function geof:aggConvexHull calculates the convex hull of the set of given geometries.

8.10.6  aggUnion

geof:aggUnion (geom: ogc:geomLiteral): ogc:geomLiteral

The function geof:aggUnion calculates the union of the set of given geometries.

9.2.1  relate

geof:relate (geom1: ogc:geomLiteral,
             geom2: ogc:geomLiteral,
             pattern-matrix: xsd:string): xsd:boolean

Figure 4

Returns true if the spatial relationship between geom1 and geom2 corresponds to one with acceptable values for the specified pattern-matrix. Otherwise, this function returns false. pattern-matrix represents a DE-9IM intersection pattern consisting of T (true) and F (false) values. The spatial reference system for geom1 is used for spatial calculations.

10.3.1  Geometry Class Hierarchy

The Simple Features specification presents a geometry class hierarchy. It is straightforward to represent this class hierarchy in RDFS and OWL by constructing IRIs for geometry classes using the following pattern: http://www.opengis.net/ont/sf#{geometry class} and by asserting appropriate rdfs:subClassOf statements. The Simple Features Vocabulary resource within GeoSPARQL 1.1 (sibling resource to this specification) does this. The following list gives the class hierarchy with each indented item being a subclass of the item in the line above. The class hierarchy starts with GeoSPARQL’s Geometry class of which sf:Geometry is a subclass:

geo:Geometry
    sf:Geometry
        sf:Curve
            sf:LineString
                sf:Line
                sf:LinearRing
        sf:GeometryCollection
            sf:MultiCurve
                sf:MultiLineString
            sf:MultiPoint
            sf:MultiSurface
                sf:MultiPolygon
        sf:Point
        sf:Surface
            sf:Polygon
                sf:Envelope
                sf:Triangle
            sf:PolyhedralSurface
                sf:TIN

The following example RDF snippet below encodes the Simple Features vocabulary Polygon class:

sf:Polygon
    a rdfs:Class, owl:Class ;
    rdfs:isDefinedBy <http://www.opengis.net/ont/sf> ;
    skos:prefLabel "Polygon"@en ;
    rdfs:subClassOf sf:Surface ;
    skos:definition "A planar surface defined by 1 exterior boundary and 0 or
                    more interior boundaries"@en ;
.

10.4.1  Geometry Class Hierarchy

An RDF/OWL class hierarchy can be generated from the GML schema that implements GM_Object by constructing IRIs for geometry classes using the following pattern: http://www.opengis.net/ont/gml#{GML Element} and by asserting appropriate rdfs:subClassOf statements.

The example RDF snippet below encodes the Polygon class from GML 3.2.

gml:Polygon
    a rdfs:Class, owl:Class ;
    skos:prefLabel "Polygon"@en ;
    rdfs:subClassOf gml:SurfacePatch ;
    skos:definition "A planar surface defined by 1 exterior boundary and 0 or
                    more interior boundaries."@en ;
.