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Interactive Navigation of Large Graphs and Networks
Tamara MunznerStanford University Graphics Group, CS Dept
Overview
Cognitive psychology wish listInfoVis problemsGraph drawing examples
graph == network node-link as in graph theory not bar charts
Interaction
Fluid interaction is hallmark of modern CG
Can create non-real environments Example: navigation
RW: rigid motion across fixed terrain CG: distortion, warping of
structure/spacewhen (if ever) is this useful?
Wanted: Prescriptive Advice
Have for static 2D Gestalt, Bertin, Mackinlay, etc
My wish list: dynamic, spatial
when are distortion (focus+context) systems useful?
Process
[Distill domain knowledge into explicit problem statement]
Find visual technique(s) to help solve problem with preattentive processing
Feedback: is system solving problem? Are they using it? Does it help?
CP wish list, cont.
Analyze what’s good when: Tease apart complex visual metaphors
into constituent low-level components Conceptual framework, user studies
Backmapping: once know what it’s good for, what other domains can be abstracted into this problem?
Problems
Scalability real-world datasets consistently outstrip tools
Efficacy lack of rigor in evaluating viz systems
Novelty creating new visual metaphors is difficult
Adoption end user buy-in
Graph drawing: traditional
Static++ interactivity not inherent pan/scroll/zoom substitute for really big paper
Does not scale small (dozens, hundreds, maybe thousands) aggregation/abstraction of large datasets
great for expository, poor for exploratory
spring-force, circular, hierarchical, etc dot, daVinci, Tom Sawyer, etc
Three Interactive Systems
Geographic: Planet MulticastHyperbolic: H3/H3ViewerImportance gradient: Constellation
Geographic: Planet Multicast
Target users: Mbone maintainersTechnique: arcs on globe [Eick95]Task: identify long-haul
misconfigurations
Planet Multicast excerpt
Interaction techniques: click on arc for tunnel info rotate globe around center
selective occlusion
rotate around point on surfacehorizon view disambiguates
PM analysis
Visual popout: long-distance links cluttered tunnel topology
Literal & natural: no explanations needed
Filtering: intercity not intracity 4000 -> 700 hemisphere occlusion
PM efficacy
geog distance only approximates bottleneck sources ideal data uncollectable few false positives, many false negatives
IP address -> lat/lon mapping infeasibleAdoption:
maintainer coauthor during developmentDoes it help?
Anecdotal
Hyperbolic: H3Viewer
Target users: webmasters, gawkersTechnique:
uses 3D hyperbolic space for recursive hemispherical layout and navigation
spanning tree backbone with nontree links drawn on demand
guaranteed frame rate drawing algorithmTask: show context of surfing choices
H3Viewer video
H3 analysis
Visual popout: subtree clusters
Filtering: spanning tree in default case
Scalability: >100,000 nodes
H3 Efficacy
Adoption: Ships with SGI Irix 6.2-6.5
minor user testinguser feedback in the wild extremely minimal
PD code, other developersnetworking, genetic algorithms
Does it help? Real user study prelim results promising
Importance Gradient: Constellation
Target users: two linguists at MSRTechniques:
custom spatial layout, horiz gradient careful use of HSV to minimize clutter
impactTask: debug semantic network
creation find implausible computed paths
Constellation video
Constellation analysis
Visual popout: hotspots, highlighted structures
Filtering: none design principle of avoiding hidden state
Adoption: TBD still under development pros and cons of tiny user community
Conclusion
Key problem in the field: Evaluating efficacy Scalability
Exploration of the design space three quite different GD systems
Acknowledgements
Planet Multicast: Eric Hoffman, Kim Claffy, Bill Fenner
Site Manager: Greg Ferguson, Alan Braverman, Ken
KershnerConstellation:
Francois Guimbretiere, George RobertsonAdvisor: Pat Hanrahan
More info
http://graphics.stanford.edu/~munzner papers talks software