Re: CRS specification

Hi,

 GeoSPARQL took most of the functions that check or return properties of
>> a geometry (all but SRID if I am not mistaken) and defined properties
>> with the
>> same name (e.g., the properties geo:isEmpty, geo:isSimple) so that one
>> would
>> be able to assert whether a geometry is empty etc. This is defined at the
>> Geometry Extension component of GeoSPARQL.
>>
>
> Yes, correct. Could you please provide the link to the owl file (if it
> exists) where the Geometry Extension component of GeoSPARQL (vocabulary) is
> defined? And can you confirm that this vocabulary does not yet contain a
> specific property that could be used to indicate the CRS used in a
> particular geometry?


The complete set of files can be found here:
http://schemas.opengis.net/geosparql/geosparql-1_0_1.zip
GeoSPARQL follows a modular architecture and some extensions can be
parameterized according to several parameters (e.g., WKT or GML
serialization standards). The files ./gml/3.2.1/gml_32_geometries.rdf and
./sf/1.0/simple_features_geometries.rdf provide information about the
respective serialization standards, and
./geosparql/1.0.1/geosparql_vocab_all.rdf contains the complete GeoSPARQL
vocabulary.

The definition of the classes geo:SpatialObject and geo:Feature is defined
at the Core extension.

The Geometry extension defines the class geo:Geometry, the properties:
geo:hasGeometry, geo:hasDefaultGeometry, geo:dimension,
geo:spatialDimension, geo:coordinateDimension, geo:isEmpty, geo:isSimple,
geo:hasSerialization, geo:asWKT, geo:asGML and the datatypes geo:wktLiteral
and geo:gmlLiteral. This extension defines some function (boundary,
envelope, union, convexHull, distance) that is not relevant to our
discussion.

The Topology Vocabulary Extension defines a set of properties
(geo:sfContains, geo:sfCrosses, geo:sfEquals etc.) with domain and range a
geo:SpatialObject that allows the user to assert that a specific
topological relationship holds between two spatial objects. This vocabulary
is intended to be used by reasoners and could be used in the context of the
locn vocabulary in order to allow users to define for example neighboring
locations.

The Geometry topology extension defines a set of SPARQL extension functions
like sfEquals, sfContaines etc.

Cheers,
Kostis