Visualising Multiple Overlapping Hierarchies

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My first workshop presentation, describing problems of multiple taxonomies in biology.


  • 1. Visualising MultipleOverlapping HierarchiesMartin Graham, Jessie Kennedy, & Chris HandNapier University, Edinburgh

2. Overview Introduction Problem Domain Current visualisation techniques Proposed Techniques Prototype Conclusions 3. IntroductionTaxonomyRoyal Botanic Garden EdinburghMultiple overlapping hierarchiesIn general occur where a hierarchicalstructure is re-organisedTaxonomy (our domain)Document categorisation etcNo 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. 5. Multiple Classifications 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. 7. Current paper-basedtaxonomy 8. The problem No current suitable paper-based method for inspecting multiple overlapping taxonomies Investigate current computer-based visualisations 9. Previous visualisationsVisualisations have been used for viewinghierarchical structures, e.g. file directoriesExamples:Cone Trees - Robertson et alInformation Pyramids - Andrews 10. Cone Trees 1991 ACM - Cone Trees: Animated 3D Visualizations of Hierarchical Information - Copy by permission of the Association of Computing Machinery 11. Andrews InformationPyramids Information Pyramids is IICM, Graz University of Technology, Austria 12. Issues for Single TreesIssues arising show that visualising evenone tree has problemsLeaves displayed - internal structuremaskedSpace issuesOcclusion when 3D usedSo visualising one tree is a problem 13. Visualisation techniques formultiple treesTwo main techniques used:Animation - showing development over timeHuang & Eades huge graphs also Wittenburgs TreeViewerSmall Multiples - showing development overphysical spaceChis Evolution of Web EcologiesTreemaps - Shneiderman & Johnson 14. Huangs on-line visualisationof a website Dept. of Computer Science and Software Engineering, University of Newcastle, NSW, Australia 15. Chi et als Web EcologyViewer User Interface Research Group - Xerox PARC 16. Multiple TreeMap Comparison Human-Computer Interaction Laboratory, Dept. of Computer Science, University of Maryland, USA 17. Issues for multiple treesAnimationDirect visual comparison between two statesonly.Works best for gradual changes, not newstructures.Small MultiplesLack of space on-screen due to repeatingdataLacks strong pre-attentive cues 18. The Problem to be visualised Need to develop appropriate visualisations to tackle these problems Time/space trade-off 19. Initial Design Sketch (1) 20. Initial Design Sketch (2)Ability to track a sub-tree (genus -grouping of specimens) across multiplehierarchies 21. Initial Design Sketch (3)Filter out unwanted pieces of information 22. Prototype 23. Conclusions Need for visualising multiple hierarchies Current visualisation techniques inadequate Initial solutions Continuing work Prototyping User evaluation/feedback 24. Acknowledgements Royal Botanic Garden, Edinburgh EPSRC