Progressive Value Reading: The Use of Motion to Gradually Examine Data Involving Large Magnitudes
People often struggle to interpret data with extremely large or small values, or ranges spanning multiple orders of magnitude. While traditional approaches, such as log scales and multiscale visualizations, can help, we explore in this article a different approach used in some emerging designs: the use of motion to let viewers gradually experience magnitude -- for example, interactive graphics that require long scrolling or street paintings stretching hundreds of meters. This approach typically demands substantial time and sustained interaction, translating differences in magnitude into a visceral sense of duration and effort. Although largely underexplored, this design strategy offers new opportunities. We introduce the term progressive value reading to refer to the use of motion to progressively examine an information object that encodes a value, where the amount of motion reflects the value. We compiled a corpus of 55 real-life and hypothetical visualization examples that allow, encourage, or require progressive value reading. From this corpus, we derived a design space of ten design dimensions, providing a shared vocabulary, inspiration for novel techniques, and a foundation for empirical evaluation. An online corpus is also available for exploration.