3. Introduction
Taxonomy
Royal Botanic Garden Edinburgh
Multiple overlapping hierarchies
In general occur where a hierarchical
structure is re-organised
Taxonomy (our domain)
Document categorisation etc
No current visualisations support them
4. What is a Taxonomy?
A methodology for classifying data. In our
case, botanical specimens.
As knowledge increases or opinions
change, new classification hierarchies
(taxonomies) are published
These taxonomies co-exist.
They do not replace each other.
Leads to accumulation of multiple
overlapping taxonomies.
6. Taxonomists need to..
Track a specimen across several
classifications
View the progress of a group of
specimens across classifications
Filter out unwanted pieces of information
We require a visualisation that can help
taxonomists perform these tasks.
8. The problem
No current suitable paper-based method
for inspecting multiple overlapping
taxonomies
Investigate current computer-based
visualisations
9. Previous visualisations
Visualisations have been used for viewing
hierarchical structures, e.g. file directories
Examples:
Cone Trees - Robertson et al
Information Pyramids - Andrews
12. Issues for Single Trees
Issues arising show that visualising even
one tree has problems
Leaves displayed - internal structure
masked
Space issues
Occlusion when 3D used
So visualising one tree is a problem
13. Visualisation techniques for
multiple trees
Two main techniques used:
Animation - showing development over time
Huang & Eades huge graphs
• also Wittenburg’s TreeViewer
Small Multiples - showing development over
physical space
Chi’s Evolution of Web Ecologies
Treemaps - Shneiderman & Johnson
17. Issues for multiple trees
Animation
Direct visual comparison between two states
only.
Works best for gradual changes, not new
structures.
Small Multiples
Lack of space on-screen due to repeating
data
Lacks strong pre-attentive cues
18. The Problem to be visualised
Need to develop appropriate
visualisations to tackle these problems
Time/space trade-off
23. Conclusions
Need for visualising multiple hierarchies
Current visualisation techniques
inadequate
Initial solutions
Continuing work
Prototyping
User evaluation/feedback