Exploratory visualization of earth science data in a Semantic Web context
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TWC Exploratory visualization of earth science
data in a semantic web context
Xiaogang (Marshall) Ma, Peter Fox
Tetherless World Constellation
Rensselaer Polytechnic Institute
AGU Fall Meeting 2012, San Francisco,
Session IN53D. Semantics and Cyberinfrastructures for Next Generation Science II
12/07/2012
TWC What is exploratory visualization
• “the process that involves a discipline
expert creating maps and other
graphics while dealing with relatively
unknown geographic data”
• “Visualization too often becomes an
end product of scientific analysis,
rather than an exploration tool that
scientists can use throughout the
research life cycle.”
(Kraak, 2008)
(Fox and Hendler, 2011) 2
TWC Motivation & Objective
• (Big) Motivation
– Online services of earth science data have been
increasingly built in recent years.
– Tools and services supporting information retrieval with
those data services are still underdeveloped.
• (Small) Objective
– A pilot study: Annotation, visualization, and filtration of
rock age (geologic time) information from online
geological map services
…
3
TWC Idea
Data Information Knowledge
Context
Presentation
Organization
Integration
Conversation
Creation
Gathering
Experience
4
TWC
5
Idea
Ontology
Data Information Knowledge
Context
Presentation
Organization
Integration
Conversation
Creation
Gathering
Experience
Geological
map
services
Exploratory
Visualization
Semantic Web
TWC Actions
• Data source: reuse available services
• Annotation: build and reuse ontologies
• Visualization: a channel between rock age data
services and annotation and
filtration operations
• Filtration: a sample of exploratory
visualization
6
TWC Data source
• Web Map Service (WMS) of British Geological
Survey
– WMS: a HTTP interface for requesting geo-registered
map images from distributed geospatial databases (http://www.opengeospatial.org/standards/wms)
• WMS operations
– GetCapabilities (mandatory), GetMap (mandatory),
GetFeatureInfo (optional)
– SLD WMS only: DescribeLayer, GetLegendGraphic,
GetStyles, PutStyles, etc.
SLD: Styled Layer Descriptor - an XML schema 7
TWC A sample of ‘GetFeatureInfo’
Output format:
• Text/xml
• Text/html
• Text/plain
…
1) Click a feature 2) Information returned
8
TWC Annotation: build and reuse
ontologies
• An ontology of geologic time scale (GTS)
– Ordinal hierarchical structure
A 7-level hierarchy
Ordinal arrangement of concepts at each level
– 175 concepts
e.g., Triassic, Middle Triassic, Induan, etc.
– Definition of concepts
Reuse existing works
– Encoding
SKOS, RDFS, OWL
9
TWC
Ordinal hierarchical structure
“Lower Triassic” in the hierarchy
10
Triassicgts:
supersetOfgts:
subsetOfLower_Triassic
Middle_Triassic
Lopingian
gts:upperThan
gts:lowerThan
Induan
Olenekian
gts:lowerThan
isA
Series
RDF triples
TWC
Definitions of
geological time
concepts
Global Boundary Stratotype Section
and Point (GSSP) information
RGB codes of geological time concepts
Multilingual labels
11
Learn ideas and
take lessons from
existing works
Refer to and reuse existing works for definitions
11
TWC
1) Get a concept (e.g., Triassic)
by clicking a feature
Annotation
function
12 2) Retrieve its annotation
from the ontology
Map: 1:625k bed
rock age of UK
TWC Visualization
• Based on the GTS ontology
– ordinal hierarchical structure, labels, color codes
• Linked to WMS map layers and the GTS ontology
for annotation and filtration operations
• Tools: ActionScript and Flare library
– Result: Flash animations
13
TWC
Rooted tree
Radial tree
(“Pie”)
14
Flash animations
TWC Filtration
• Show legend of a WMS map layer in the
animation
• Use the legend as a control panel to show spatial
features of certain GTS concept(s)
• Tools: JavaScript, OpenLayers and SLD
– SLD: an XML schema describing the appearance of
map layers
15
TWC Show Legend: SLD from WMS
1) WMS operation:
GetStyles
2) Get a list of geologic
time concepts from the
SLD document 3) Generate a Legend for
the WMS map layer
16
TWC
Courtesy OneGeology-Europe
Surface rock age (1 : 1M)
More examples
Germany
TWC Surface rock age (1 : 1M)
Courtesy OneGeology-Europe
Norway
TWC Maps of participants in OneGeology-Europe
TWC Maps of participants in OneGeology-Europe
Denmark Surface rock age (1 : 1M)
TWC Show features: SLD to WMS
1) Click “Upper Cretaceous”
in the legend
2) Generate an SLD document
for “Upper Cretaceous”, by
referring the GTS ontology
4) Get features of
“Upper Cretaceous”
21 3) Send the SLD to WMS server
TWC Filter & generalize geological time features using the legend
TWC
Generalization at System level Generalization at Erathem level
Generalization at Eonothem level “Precambrian” and “Phanerozoic”
More examples of generalization
TWC Current work
• Collaborate with GeoSciML group to refine the
geologic time ontology
– http://resource.geosciml.org/vocabulary/timescale/
– Dr. Simon Cox (CSIRO), Dr. Steve Richard (AZGS)
• Use d3.js to rebuild the visualization
• Use triple store to hold the ontology, and SPARQL
for query
• Reuse Linked Data resources for annotation
– DBpedia, SISSVoc
25
TWC New Demo
WMS + Flash + Ontology file + JavaScript
http://goo.gl/tyDKL
WMS + D3.js Viz + Ontology in triple store + JavaScript
http://goo.gl/WghdY
26
TWC Wrap up
• Exploratory visualization provides a intuitive way to show
patterns of ontologies and data
• Ontology is a powerful aid for conducting exploratory
visualization
• Semantic Web provides a space for retrieving more data
and, hopefully, more information
• Further efforts are needed to deploy exploratory
visualization in earth science works
27
TWC
More information:
Marshall X Ma
Thank you!
Demos:
http://goo.gl/tyDKL
http://goo.gl/WghdY
Acknowledgements: