exploratory visualization of earth science data in a semantic web context

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 Demo

WMS + Flash Viz + Vocabulary file + JavaScript

http://goo.gl/tyDKL

24

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

max7@rpi.edu

Thank you!

Demos:

http://goo.gl/tyDKL

http://goo.gl/WghdY

Acknowledgements: