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Yang Ou
School of GeoSciences
The University of Edinburgh
Expressing the Semantics of Geographic Information
and Processes
Syntactic
Semantic
data conversionSpatial Data Transfer Standard (SDTS)
Open Geodata Interoperability Specification (OGIS)
Web Services
Ontologies
Information ProcessesInteroperability
Approaches to Achieve GIS Interoperability
Describing the Semantics of Geographic Information
Model 1 Model 2 Model 3 Model n…
Ontologyconceptual level
data level
Real-world EntitiesSpatial Database
represents
geometry id name ……namegeometry id
Schemas/Data model Domain Ontology
conceptualisesmodelsimplements
Relationship between Representations of Spatial Information
Real-world Entities
Spatial Database
represents
geometry id name ……namegeometry id
Schemas/Data model
conceptualises
modelsimplements
Domain OntologyData Ontology
conceptualises
hasLocation
hasConcept
SpatialDataset
RasterDataset
PointDataset PolygonDataset
VectorDataset
LineDataset
subClassOf subClassOf
subClassOfsubClassOf subClassOf
hasLocation hasConcept
Literal
domain domain
range range
Basic Conceptualisation of Spatial Dataset in RDFS
VectorDataset ≡ SpatialDataset u = 1hasGeometry
PointDataset ≡ VectorDataset u 8hasGeometry.Point
LineDataset ≡ VectorDataset u 8hasGeometry.Line
PolygonDataset ≡ VectorDataset u 8hasGeometry.Polygon
RasterDataset ≡SpatialDataset u :VectorDataset u = 1hasResolution
SpatialDataset ≡ Dataset u = 1hasCoordinateSystem
Part of the Definition of the Data Ontology
To utilise the “semantic information”, we need “semantic processes”.
Constructing Semantic Web Services for Geospatial Processes
Point {double x; double y}
Example: there was a Web service that was providing a process to calculate the distance between two points.
double distanceBetween(Point a, Point b);
Geospatial Process
spatial data
SOAP message
ontological instance
Web Service
Semantic Web ServiceSemantic Interface
Syntactic Interface
Interoperability Structure for Geospatial Processes
Syntactic Interface
Semantic Interface
data
Atomic Process
Input handler
instance
dataset
describes
fetch data
Input Handling Process
describes
Syntactic Interface
Semantic Interface
creates
data
Atomic Process
Output handler
instance
dataset
instance
stores
Output Handling Process
Atomic Geospatial Process
Input Handling Process
Output Handling Process
spatial data
instance
instance
spatial dataAtomic Geospatial Processing Unit
A Running Example
Identifying a certain kind of facility near given locations
Process 1: Creating buffer areas of the given locations
break down into two steps
Process 2: Selecting the features that drop within the buffer areas
The Processing Unit of the Buffering Process
The Processing Unit of the Selection Process
Combination of the Two Processing
Units
Randomly Produced Layers for Testing
Virtual Data Source
Describing the Datasets in an Ontology
choose the layer to be selected
choose the layer to be buffered
specify the buffer
distance Output: the URI of the instance
that describes
the process result
explore the output URI
retrieve the spatial data of the process result through the
location property in the ontology
Visualisation of the Output Data Sets
geometry
idname
currency
population
Iceland
267240
KronaIceland
100
polygon
geometry feature_id country_name currency population
POLYGON 100 Iceland Krona 267240record
individual
A Further Idea to Apply Ontologies in GIS
Representing Geographic Information as Geographic Knowledge
Database vs. Knowledge base
hasName
hasValuehasValue hasValue
hasValue
hasNamehasName
hasName
hasValuehasValue
hasValue
hasValuehasAttribute
hasAttribute
hasAttribute
hasAttributehasGeometry
geometry feature_id country_name currency population
POLYGON 100 Iceland Krona 267240
Iceland
polygon
attribute
integer id
100 Iceland
name string Krona
currency
string
267240double
population
attribute
attribute
attribute
record
individual
Some potential advantages:
The process of such a kind of semantic geographic information doesn’t require communicating ontologies with spatial data.
Reasoning capability of ontologies can be considered to perform potential geospatial analyses.
Developing Geographic Information Systems towards Geographic Knowledge Systems.
Thank you!