Elastic Hierarchies: Combining Treemaps and Node-Link Diagrams

1. Elastic Hierarchies: Combining Treemaps and Node-Link Diagrams Shengdong Zhao, Michael J. McGuffin, Mark H. Chignell University of Toronto

2. Hierarchies (Trees) • Definition • Data where cases relate to subcases • Examples • Family histories, ancestries • File/directory systems on computers • Organization charts • Animal kingdom: phylum, genus • Object-oriented software classes

3. Common Tree Representations Alignment, Adjacency Node-Link Containment Outline

4. Common Tree Representations Alignment, Adjacency Node-Link Containment Outline Node-Link Diagram

5. Common Tree Representations Alignment, Adjacency Node-Link Containment Outline Node-Link Diagram Treemap

6. Common Tree Representations Alignment, Adjacency Node-Link Containment Outline Node-Link Diagram Treemap Sunburst

7. Common Tree Representations Alignment, Adjacency Node-Link Containment Outline Node-Link Diagram Treemap Sunburst Explorer

8. Tree Visualization Challenges • Structure AND data within items • Scalability (exponential growth) • Context (when focus changes) • Multiple hierarchies orpolyarchies • Multiple foci [Furnas & Zacks] [Robertson]

9. Tree Visualization Challenges • Different local properties • Topology (dense vs. sparse) • Data content (image vs. text)

10. Tree Visualization Challenges • Different local properties • Topology (dense vs. sparse) • Data content (image vs. text) • Dynamic data • Hierarchies evolve • Adjustment required for content, context, topology

11. Single Representation Limitations Node-Link Diagram Treemap Sunburst Explorer

12. Single Representation Limitations • Structure vs. data within items Node-Link Diagram Treemap Sunburst Explorer

13. Single Representation Limitations • Structure vs. data within items • Expressivity Node-Link Diagram Treemap Sunburst Explorer

14. Single Representation Limitations • Structure vs. data within items • Expressivity • Static representation Node-Link Diagram Treemap Sunburst Explorer

15. Single Representation Limitations • Structure vs. data within items • Expressivity • Static representation Node-Link Diagram Treemap Sunburst Explorer

16. Node-Link & Treemap

17. Node-Link & Treemap

18. Node-Link & Treemap

19. Node-Link & Treemap

20. Solving the Problem • Hybridize complementary representations to balance structure and scalability

21. Solving the Problem • Hybridize complementary representations to balance structure and scalability • Representational adaptations for branches and tasks

22. Solving the Problem • Hybridize complementary representations to balance structure and scalability • Representational adaptations for branches and tasks • User manipulation and automatic adjustment

23. Combine Multiple Representations Node-Link

24. Combine Multiple Representations Node-Link Treemap

25. Combine Multiple Representations Node-Link Hybrid 1 Treemap

26. Combine Multiple Representations Node-Link Hybrid 1 Hybrid 2 Treemap

27. Combine Multiple Representations … … … Node-Link Hybrid 1 Hybrid 2 Treemap

28. Combine Multiple Representations … … … Node-Link Hybrid 1 Hybrid 2 Treemap Elastic Hierarchy: Entire set of adjustable hybrids of multiple representations

29. Elastic Hierarchy A tree of ~3500 nodes using Node-Link Node–Link Diagram

30. Elastic Hierarchy Same tree using Treemap Treemap

31. Elastic Hierarchy Same tree using Elastic Hierarchy Elastic Hierarchy

32. Elastic Hierarchy • Elastic Hierarchy • Focus+context • Adaptability+user control • Multiple foci Node–Link Diagram Treemap Elastic Hierarchy

33. x y Taxonomy

34. x y Taxonomy Node-Link (NL) Treemap (TM)

35. x y Taxonomy Node-Link (NL) Treemap (TM) inside outside

36. x y Taxonomy Node-Link (NL) Treemap (TM) inside outside NL outside NL …….(A) TM outside NL …….(B) NL outside TM …….(C) TM outside TM …….(D) NL inside TM …….(E) TM inside TM …….(F) NL inside NL …….(G) TM inside NL …….(H)

37. x y Taxonomy Node-Link (NL) Treemap (TM) inside outside NL outside NL …….(A) TM outside NL …….(B) NL outside TM …….(C) TM outside TM …….(D) NL inside TM …….(E) TM inside TM …….(F) NL inside NL …….(G) TM inside NL …….(H)

38. x y Taxonomy Node-Link (NL) Treemap (TM) inside outside NL outside NL …….(A) TM outside NL …….(B) NL outside TM …….(C) TM outside TM …….(D) NL inside TM …….(E) TM inside TM …….(F)

39. x y Taxonomy Node-Link (NL) Treemap (TM) inside outside NL outside NL …….(A) TM outside NL …….(B) NL outside TM …….(C) TM outside TM …….(D) NL inside TM …….(E) TM inside TM …….(F)

40. x y Taxonomy Node-Link (NL) Treemap (TM) inside outside NL outside NL …….(A) TM outside NL …….(B) NL outside TM …….(C) TM outside TM …….(D) NL inside TM …….(E) TM inside TM …….(F)

41. Treemap Outside Node-Link

42. Treemap Outside Node-Link • Preserve top-level topology

43. Treemap Outside Node-Link • Preserve top-level topology • Space filling at crowded lower levels

44. Treemap Outside Node-Link • Preserve top-level topology • Space filling at crowded lower levels • Pattern comparison among branches

45. Treemap/Node-Link Outside Treemap

46. Treemap/Node-Link Outside Treemap • Focus+Context

47. Treemap/Node-Link Outside Treemap • Focus+Context • Multiple foci

48. Treemap/Node-Link Outside Treemap • Focus+Context • Multiple foci • Occlusion

49. Node-Link Inside Treemap

50. Node-Link Inside Treemap • Local topology within context • But, has tight space constrains