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2 Main Approaches
• Connection (node & link)
• outliner
• Containment (node in node)
• Venn diagram
A
CB
A
B C
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Tasks
• Help understand node characteristics or
tree structure?
• Some kinds of tasks:
– Find a node
– Revisit node
– List node ancestors
– Understand local topology
– Understand global topology
• Different Trees are good for different tasks
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Why is tree visualization hard?
– Structure AND items (Structure
harder, consumes more space)
– Scaling: data size grows very quickly
(exponential)
• #nodes = bheight
– How to provide Context (when focus
changes)
– May be multiple hierarchies
– May be multiple focuses
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Current Status
• Many 2D and 3D hierarchy visualizations
– Each works for some tasks and some scales
– Very few have had user testing
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Sunburst vs. Treemap
• + Faster learning time: like pie chart
• + Details outward, instead of inward
• + Focus+context zooming
• - Not space filling
• - More space used by non-leaves
• All leaves on 1-D space, perimeter
• Treemap: 2-D space for leaves
• - Smaller scale?
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Polyarchies
• multiple inter-twined trees
• Visual pivot
• George Robertson, Microsoft Research
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Research Questions
• Can multidimensional data per node be
portrayed?
• How does the visualization scale?
• What tasks are best supported by each vis?
• Can users quickly understand the
representation?
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• Observations
– It’s hard to preserve the structure of the tree and allow
scalability
– Different approaches are good for certain tasks with
certain scale, and one single approach often has
limitations and can’t solve a range of problems well
– Change of representations require learning
• Possible Solution
– Try a hybrid approach to balance the structure and
scalability
– Create a solution with continuous variations for a range
of tasks
– Use animation to help users to understand the
representation
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Node Link vs. Space Filling
• Advantage of Node Link
– Show Structure and Item
– Natural
• Disadvantage:
– Hard to scale (100 nodes)
• Advantage of Space Filling
– Using 100% of screen space, scalable
– monitoring and detect patterns in leaf nodes
• Disadvantage:
– Harder to see the structure
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• What about combining the two techniques
to create a continuous series of smooth
representations and use animation to help
users to understand the these representations
better
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Several Ideas
• Create animated transition between linked
tree and treemaps
Quic kTim e™ and a TIFF (LZW) decom press or are needed to see this picture.
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Intermediates
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
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Overview + Detail
QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.
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Questions
• Is this a worthwhile research topic?
• Suggestions for further directions?
• Any other combinations?
• Which variation of the hybrid model is good
for what tasks? (Scale?)
• Anything else?