FocusBased Clustering for MultiScale Visualization

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Focus-Based Clustering for Multi-Scale
Visualization

• François Boutin Mountaz Hascoët
• PhD Student Associate Professor
• francois.boutin_at_univ-montp1.fr mountaz_at_lirmm.fr
• LIRMM UMR 5506 CNRS
• University Montpellier II France
• AVI 2004

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Context

• Objectives
• Large graph clustering based on graph
  structure from a focus-node.
• Graph exploration from various perspectives
  (foci).
• Tools
• An original multi-level clustering technique
  providing a new structure called MuLOT
  Multi-Level Outline Tree
• MuLOT is a tree of meta-nodes, where
• each meta node is hierarchically clustered.

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Initial graph Spring layout
Focus
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Outline Tree Principle
G3
L3
Focus
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Outline Tree Meta-nodes
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Resulting Outline Tree
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Outline Tree - Algorithm (step 1)
L5
Process
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Outline Tree - Algorithm (step 2)
L4 - L5
Process
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Outline Tree - Algorithm (step 3)
L3- L4
Process
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Outline Tree - Algorithm (step 4)
L2 L3
Process
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Outline Tree - Algorithm (step 5)
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A Multi-level approach

• Problems
• Meta-nodes may be very large.
• Nodes in a meta-node are more or less related.
• Propositions
• Each meta-node can be hierarchically clustered
  according to relations between its nodes.
• We propose a multi-level structure called
  Multi-Level Outline Tree (MuLOT)
• MuLOT is an adjacency tree of meta-nodes.
• Each meta-node is the root of an inclusion tree
  of clusters.

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Multi-Level Outline Tree (level 0)
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Multi-Level Outline Tree (level 1)
Level 0
Process
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Multi-Level Outline Tree (level 2)
Level 0
Level 1
Process
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Multi-Level Outline Tree (level 3)
Level 0
Level 1
Level 2
Process
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Multi-Level Outline Tree
Level 0
Level 1
Level 2
Level 3
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Example Spring layout
Focus
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Example - MuLOT
Focus
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Perspectives

• Clusters cohesiveness definition
•  Cluster Validity Indices for Graph
  Partitioning , Boutin François, Hascoët Mountaz,
  IV04
• Citation graph navigation
•  Multi-Level Exploration of Citation Graphs ,
  Boutin François, Hascoët Mountaz, submitted to
  ECDL 2004
• MuLOT Layout and interaction
•  Interaction and Visualisation supporting web
  browsing patterns , Hascoët Mountaz, IV01
• User evaluations