Clarity and Computational Efficiency of Orbital Boundary Labeling

TL;DR

This paper introduces algorithms for orbital boundary labeling on circular interfaces, optimizing leader lines for clarity and efficiency, and evaluates their performance through experiments and user studies.

Contribution

It presents novel algorithms for orbital boundary labeling with crossing-free shortest leaders, applicable to both uniform and non-uniform label sizes.

Findings

Straight-line leaders enable faster response times.

Both leader styles have similar accuracy.

Algorithms effectively optimize leader placement.

Abstract

Circular interfaces such as those found on smartwatches, automotive dashboards, cockpit instruments, or in radial visualizations pose unique challenges for placing readable labels. Traditional rectangular labeling methods waste screen space and create visual clutter on these constrained displays. In orbital boundary labeling, the labels (e.g., the features' names) are placed in an annulus-shaped orbit outside of the figure, and each label is connected to its feature using a short, crossing-free leader line. We contribute algorithms to compute two leader styles, orbital-radial and straight-line, for uniform and non-uniform label sizes, optimizing for crossing-free shortest leaders. We evaluate the model and the algorithms with computational experiments and a controlled user experiment. The user experiment reveals that both leader types exhibit similar accuracy, but straight-line leaders yield faster response times.