- Visual encoding: process of translating data into visual elements
- Marks: basic geometric elements depicting data or links
- Special marks
- Connection: relationship
- Containment: hierarchical relationships
- Channels: control the appearance of marks
- e.g. position, color, shape, size
- Magnitude: how much
- Pie charts
- Bar charts in a different form
- Human eye can understand difference between lengths faster than angles
- But can be visually appealing
- Identity: what/where/when
- Effectiveness: important attributes should match most noticeable
- Best channels
- Position
- Length
- Spatial region
- Color
- Perceptual principles
- Accuracy: how close perception matches reality
- Discriminability: ability to differentiate between items; distinctness
- Separability: independence from each other
- Weber’s Law: Contrast effect - human perception is based on relative comparisons
- Framing: reference point used to present data
- Alignment: positioning of data points relative to each other