Download Interactive Navigation of Large Graphs and Networks

Interactive Navigation of
Large Graphs and
Networks
Tamara Munzner
Stanford University
Graphics Group, CS Dept
Overview
Cognitive psychology wish list
InfoVis problems
Graph 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/space
when (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
Three Interactive Systems
Geographic: Planet Multicast
Hyperbolic: H3/H3Viewer
Importance gradient: Constellation
Geographic: Planet Multicast
Target users: Mbone maintainers
Technique: 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 surface
horizon 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 infeasible
Adoption:
maintainer coauthor during development
Does it help?
Anecdotal
Hyperbolic: H3Viewer
Target users: webmasters, gawkers
Technique:
uses 3D hyperbolic space for recursive
hemispherical layout and navigation
spanning tree backbone with nontree links
drawn on demand
guaranteed frame rate drawing algorithm
Task: 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 testing
user feedback in the wild extremely minimal
PD code, other developers
networking, genetic algorithms
Does it help?
Real user study prelim results promising
Importance Gradient:
Constellation
Target users: two linguists at MSR
Techniques:
custom spatial layout, horiz gradient
careful use of HSV to minimize clutter impact
Task: 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
Kershner
Constellation:
Francois Guimbretiere, George Robertson
Advisor: Pat Hanrahan
More info
http://graphics.stanford.edu/~munzner
papers
talks
software