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