Transitions in Dynamic Point Labeling

TL;DR

This paper explores how to smoothly transition point labelings on maps in dynamic settings, analyzing overlaps, computational complexity, and practical implementation for geotagged data.

Contribution

It introduces new transition types for dynamic point labelings, provides bounds on overlaps, and assesses computational complexity and practical performance.

Findings

Tight bounds on overlaps during label transitions

NP-completeness of penalty minimization in simultaneous transitions

Prototype implementation evaluating transition styles

Abstract

The labeling of point features on a map is a well-studied topic. In a static setting, the goal is to find a non-overlapping label placement for (a subset of) point features. In a dynamic setting, the set of point features and their corresponding labels change, and the labeling has to adapt to such changes. To aid the user in tracking these changes, we can use morphs, here called transitions, to indicate how a labeling changes. Such transitions have not gained much attention yet, and we investigate different types of transitions for labelings of points, most notably consecutive transitions and simultaneous transitions. We give (tight) upper bounds on the number of overlaps that can occur during these transitions. When each label has a non-negative weight associated to it, and each overlap imposes a penalty proportional to the weight of the overlapping labels, we show that it is NP-complete to decide whether the penalty during a simultaneous transition has weight at most $k$. Finally, we consider geotagged data on a map, by labeling points with rectangular or square labels. We developed a prototype implementation to evaluate different transition styles in practice, measuring both number of overlaps and transition duration.