StarLion: Auto-configurable Layouts for Exploring Ontologies
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Transcript of StarLion: Auto-configurable Layouts for Exploring Ontologies
StarLion: Auto-configurable Layouts forExploring Ontologies
Stamatis Zampetakis, Yannis Tzitzikas,Asterios Leonidis, and Dimitris Kotzinos
Institute of Computer Science, FORTH-ICS, Greece, andComputer Science Department, University of Crete, Greece
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OutlineMotivationStarLion
Exploration MethodLayout AlgorithmOntology Dependencies
Conclusion
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Motivation It is difficult to understand a big RDFS
ontology, even if it is visualized (here as a labeled directed graph)
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Exploration through Star ViewsWe propose exploring gradually the ontology
through StarViewsthe user selects one class c as a focal point. Class c along with all
related classes in distance (radius) k from c are visualized creating Star-like graphs
StarView on class Actor with radius 1
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Exploration through Star GraphsExample
Cidoc CRM Ontology
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Exploration through Star GraphsExample (cont)
StarView On Class Actor with Radius 1
StarView on E39 Actor with Radius = 1
Click on E30 Right
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Exploration through Star GraphsExample (cont)StarView on E30 Right with Radius = 1
StarView on Class Right with radius 1
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Exploration through Star Graphs
Example (cont): Increasing the Radius
StarView on Class Right with radius 2
StarView on E30 Right with Radius = 2
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StarViews can also be used for data explorationdata usually come in big volumes which cannot be
visualized altogether
Exploration through Star Graphs
Example : Data Visualization
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How to layout these graphs?Observations and RequirementsEvery graph has different features:
Different number of nodes, edges, isA (subclass-superclass) relations
The layout algorithm that will be used, must be configurable for adapting to every occasion
Our approach Adopt a force-directed placement algorithm
(FDPA) and focus on the configuration of its parameters
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A force-directed placement algorithm for RDFS
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Person
company
Manager
Secretary
Person
company
Manager
Secretary
worksAt
subClassOfsubClassOf
We view an RDF schema as a mechanical system
Magnet Magnetic Field
ElectricalRepulsion
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A force-directed placement algorithm for RDFS >Configuration
FDPA has three parameters that affect the produced layoutKm – magnetic field strengthKe – repulsion strength L – spring length
Our approach• A toolbar for relative configuration• A “Magic button”
• quality metrics and automatic configuration
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Configuring the ParametersToolbar for Relative Configuration
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Configuring the ParametersThe “Magic Button”It measures the quality
of the layout based on two metricsVerticality of
specialization hierarchies and
Layout areaThen it re-adjusts the
configuration parameters for improving the layout
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Configuring the ParametersThe “Magic Button”> Example The layout with a simple application of the FDPA without any configuration
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Configuring the ParametersThe “Magic Button”> Example After 1 application of the FDPA with automatic configuration
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Configuring the ParametersThe “Magic Button”> Example After 2 applications of the FDPA with automatic configuration
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Visualization of Ontology DependenciesOntologies usually extend other ontologies In most cases visualizing parts of the related
ontologies is crucial for the understanding of the main ontology
Our ApproachWe support three options for the visualization of an
ontology’s dependenciesDirect Dependencies: Main ontology + Only the directly
connected elements from the other related ontologiesTransitive Dependencies: Main ontology + Directly
connected elements from the other related ontologies along with their superclasses
Full Dependencies: Visualize all related ontologies entirely
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Visualization of Dependent Namespaces> Example
Cidoc CRM Ontology
Cidoc CRM Digital
Ontology
Extends
Example:Cidoc CRM Ditital Ontology extends Cidoc CRM Ontology adding six new classes and a few properties
By visualizing Cidoc CRM Digital Ontology alone we get:
By visualizing Cidoc CRM Digital Ontology taking into account its dependency we get.
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ConclusionIn comparison with related works and systems:
Most of them do not support variable radius in StarView
None of them uses a FDPA that takes into account the subClassOf hierarchies
Most of them do not allow configuring the FDPA parameters
They do not support auto-configuration of the FDPA parameters
They do not exploit dependencies between ontologies in the visualization
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THANKS FOR YOUR ATTENTION