1. Fractal Perspective
A Visualization Technique for Semantic Networks
IV2011
Curran Kelleher
University of Massachusetts Lowell
Institute for Visualization and Perception Research

2. Outline
● Related work
● RDF, the Semantic Web
● Node-Link RDF visualization, TreeMaps
● The Fractal Perspective Technique
● A “Perspective Projection” from a semantic graph
● Incremental layout technique, implementation steps
● Advantages, disadvantages
● Future Directions
● Toward user-definable RDF-driven visual languages

3. The Semantic Web Layer Cake
Official diagram
from the
World Wide Web
Consortium

4. Example RDF Data
<?xml version="1.0"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:contact="http://www.w3.org/2000/10/swap/pim/contact#">
<contact:Person rdf:about="http://www.w3.org/People/EM/contact#me">
<contact:fullName>Eric Miller</contact:fullName>
<contact:mailbox rdf:resource="mailto:em@w3.org"/>
<contact:personalTitle>Dr.</contact:personalTitle>
</contact:Person>
</rdf:RDF>
Figure by the World Wide Web Consortium 2009

5. Related Work: Tree Maps
Treemap View of 2004 Usenet Returnees scimaps.org/maps/map/treemap_view_of_2004_57/

6. Related Work: Voronoi Tree Maps
M. Balzer, O. Deussen. “Voronoi Treemaps”. IEEE Symposium on Information Visualization (InfoVis), 2005

7. Related Work: Circular Tree Maps
1. K. Wetzel. “Pebbles - using Circular Treemaps to visualize disk usage”.
Web resource, accessed 3/2/2011 from
http://lip.sourceforge.net/ctreemap.html
2. Lizorkin, Medelyan, Grineva. “Analysis of Community Structure in
Wikipedia” (Poster). 18th International World Wide Web Conference. 2009.
3. Wikipedia contributors. "Sustainability." Wikipedia, The Free Encyclopedia.
Wikipedia, The Free Encyclopedia, 20 Mar. 2011. Web. 21 Mar. 2011.
4. Using the Nested Set Data Model for Breadcrumb Links. Jason Mauss.
2005. Retrieved 3/02/2011 from
http://www.developer.com/db/article.php/3517366/Using-the-Nested-Set-
Data-Model-for-Breadcrumb-Links.htm

8. Original Intent: Visual Navigation of
Hierarchical Data Cube Dimensions
● Part of a multi-touch computing course project
● First pass prototype: visualize countries of the
world and their populations, from DBPedia

10. HTML5 + Processing JS + iPad
• HTML5 Canvas supported
on the iPad
• Processing.js is a library for running
Processing programs in HTML5
• Easy to pass iPad multi-touch
events into Processing code
-->
that code
produces this
interactive graphic
<--
example code and image from http://processingjs.org/learning

12. SPARQL: Querying RDF
Some RDF data:
A SPARQL query:
The task at hand:
subgraph matching
(alignment of SPARQL query variables with triples)
Figures by Kurt Rohloff, taken from slides available at
http://www.dist-systems.bbn.com/people/krohloff/papers/2011/Rohloff_Meetup_01_09_2011.pdf
SELECT ?person
WHERE {
?person :owns ?car .
?car a :Car .
?car :madeIn :Detroit .
}

13. Querying DBPedia
• DBPedia is an RDF graph scraped from Wikipedia
• Here's an example query construction in Javascript:
•
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• Here are
some
results:

15. Circle Layout
• Tried various force functions
• Best emergent behavior from
the Sigmoid function
The force field
between circles
The force field
of the outer circle
Images generated using Wolfram Alpha: enter Plot3D[1/(1+pow(2,(sqrt(x^2+y^2)-10)*6)), {x, -12, 12}, {y, -12, 12}]

16. Fractal Perspective
• A new idea: navigating semantic graphs with nested objects
• Navigation like cartographic maps (pan, zoom)
• Incremental evaluation fits with Linked Data paradigm

17. Idea: Visual Languages for
Exploring the Semantic Web
● RDF class → a visual type encoding
● Glyphs, styles
● RDF property → a visual property encoding
● Nested object, object modification
● Goal: Make legends interactively editable
● Toward user-definable visual languages

18. The End.