Geometric zoom: standard, like moving physical object
Semantic zoom: keep objects same size, but change the scale/viewport
Idiom: Semantic Zooming
Semantic Zoom
Alternative to geometric zoom
Resolution-aware layout adapts to available space
Goal: legible at multiple scales
Dramatic or subtle effects
Visual encoding change
Colored box
Sparkline
Simple line chart
Full chart: axes and tickmarks
[LiveRAC - Interactive Visual Exploration of System Management Time-Series Data. McLachlan, Munzner, Koutsofios, and North. Proc. ACM Conf. Human Factors in Computing Systems (CHI), pp. 1483–1492, 2008.]
LiveRAC
Geometric Zoom
Semantic Zoom
Rotate
Zoom to Constrained
Transition and Animated Navigation
Barchart Race
Interaction Benefits
Interaction Pros
Major advantage of computer-based vs. paper-based visualization
Flexible, powerful, intuitive
Exploratory data analysis: change as you go during analysis process
Fluid task switching: different visual encodings support different tasks
Animated transitions provide excellent support
Empirical evidence that animated transitions help people stay oriented
Interaction Limitations
Interaction has a time cost.
Sometimes minor, sometimes significant
Degenerates to human-powered search in worst case
Remembering previous state imposes cognitive load
Rule of thumb: eyes over memory.
Hard to compare visible item to memory of what you saw
Example: maintaining context/orientation when navigating
Example: tracking complex changes during animation
Controls may take screen real estate.
Or invisible functionality may be difficult to discover (lack of affordances)
Users may not interact as planned by designer.
NYTimes logs show about 90% don’t interact beyond scrollytelling - Aisch, 2016