Dear All,
I have just finished a draft of the section "recording space" of the
guideline "Expressing the CIDOC CRM in RDF
(https://docs.google.com/document/d/1zCGZ4iBzekcEYo4Dy0hI8CrZ7dTkMD2rJaxavtEOET0/edit#):
The recommended datatypes of RDF1.1 do not contain datatypes for
describing geometric entities on the surface of earth. On the other
side, they become increasingly important, and the CIDOC CRM version 6.2
on defines E94 Space Primitive, subclass of: E59 Primitive Value, as:
“This class comprises instances of E59 Primitive Value for space that
should be implemented with appropriate validation, precision and
references to spatial coordinate systems to express geometries on or
relative to earth, or any other stable constellations of matter,
relevant to cultural and scientific documentation.
An E94 Space Primitive defines an E53 Place in the sense of a
declarative place as elaborated in CRMgeo (Doerr and Hiebel 2013), which
means that the identity of the place is derived from its geometric
definition. This declarative place allows for the application of all
place properties to relate phenomenal places to their approximations
expressed with geometries.
Definitions of instances of E53 Place using different spatial reference
systems always result in definitions of different instances of E53 place
approximating each other. It is possible for a place to be defined by
phenomena causal to it, such as a settlement or a riverbed, or other
forms of identification rather than by an instance of E94 Space
Primitive. Any geometric approximation of such a place by an instance of
E94 Space Primitive constitutes an instance of E53 Place in its own
right, i.e., the approximating one.
Instances of E94 Space Primitive provide the ability to link CRM encoded
data to the kinds of geometries used in maps or Geoinformation systems.
They may be used for visualisation of the instances of E53 Place they
define, in their geographic context and for computing topological
relations between places based on these geometries.
E94 Space Primitive is not further elaborated upon within this model.
Compatibility with OGC standards are recommended.”
These standards currently do not have a common form comprising all
others. Further, geometries defined with respect to particular object
shapes, such as rotationally symmetric ones, are possibly open ended.
Therefore we define in the CRM RDFS the range of properties that use
*E94 Space Primitive* in the definition of the CRM as *rdfs:Literal*,
and recommend the user to instantiate it with adequate XML datatypes.
These are for the surface of Earth “*ogc:**gmlLiteral”
*or*“***geo:*wktLiteral”*.
In the current version of the CIDOC CRM, only the property “P168 place
is defined by (defines place)” has range E94 Space Primitive.
Since any instance of E94 Space Primitive identifies unambiguously an
instance of E53 Place by a symbolic expression, *E94 Space Primitive
must logically be regarded as a subclass of E41 Appellation*, regardless
whether this can be expressed in RDFS or OWL. See below for the
relationship between datatypes an E41 Appellation.
In a footnote I make the argument that:
"The concepts E47 Spatial Coordinates,crmgeo: SP5 Geometric Place
Expression, crmgeo:Q10 defines place and P168 place is defined by
(defines place) need to be revised soon.
*E94 Space Primitive should replace E47 Spatial Coordinates and SP5
Geometric Place Expression.* *P168 place is defined by (defines place)
should replace crmgeo:Q10 defines place*. It may be useful in the CRM
RDFS to specify *two subproperties of P168*, one having as range
“geo:wktLiteral” and another “ogc:gmlLiteral”.
Best,
Martin
--
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Dr. Martin Doerr | Vox:+30(2810)391625 |
Research Director | Fax:+30(2810)391638 |
| Email: mar...@ics.forth.gr |
|
Center for Cultural Informatics |
Information Systems Laboratory |
Institute of Computer Science |
Foundation for Research and Technology - Hellas (FORTH) |
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N.Plastira 100, Vassilika Vouton, |
GR70013 Heraklion,Crete,Greece |
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Web-site: http://www.ics.forth.gr/isl |
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