Visualizing Time-Varying Data
Animation and small multiples both show change over time; each has strengths, and the choice depends on the comparison the viewer must make.
The extra dimension
Time-varying data adds a dimension that must be shown somehow. The two main approaches are animation, which maps data time to playback time, and small multiples, which lay out successive states side by side in space. Each supports a different kind of reasoning.
Animation
Animation is intuitive for showing motion and continuous evolution; the eye tracks features naturally. Its weakness is comparison across time: the viewer cannot see two distant moments at once and must rely on memory. Controls (play, pause, scrub, speed) turn passive playback into inspection.
- Good for flow, propagation, and qualitative dynamics.
- Poor for precise comparison of non-adjacent times.
- Provide a scrubber and a visible clock so time is explicit.
Small multiples
Small multiples place snapshots in a grid, so all times are visible together for direct comparison. They suit reports and analysis where the reader must compare states carefully. The cost is space and per-panel resolution.
Pathlines and traces
For moving features, drawing the trajectory (a pathline or trace) encodes time into a static image, so history is visible without animation. This is the time analogue of a streamline for unsteady fields.
Honesty
Keep a fixed color scale and axis across frames; a scale that rescales each frame makes unchanged magnitudes look like change. State the frame rate and whether time is real or scaled.
Kronos use
Time-dependent simulation output is shown with fixed scales, a visible clock, and small multiples when precise comparison across instants is required.