Interactive Navigation of Large Graphs and Networks Tamara Munzner Stanford University Graphics...
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Transcript of Interactive Navigation of Large Graphs and Networks Tamara Munzner Stanford University Graphics...
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