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!