On the readability of leaders in boundary labeling. (January 2019)

• Record Type: Journal Article
• Authors: Barth, Lukas; Gemsa, Andreas; Niedermann, Benjamin; Nöllenburg, Martin
• Is Part Of: Information visualization. Volume 18:Number 1(2019)
• Page Start: 110
• Page End: 132
• Publication Date: 2019-01
• Subjects: External labeling -- boundary labeling -- user study -- readability; Information visualization -- Periodicals; 006.605
• DOI: 10.1177/1473871618799500
• Languages: English
• ISSNs: 1473-8716

Abstract

External labeling deals with annotating features in images with labels that are placed outside of the image and are connected by curves (so-called leaders) to the corresponding features. While external labeling has been extensively investigated from a perspective of automatization, the research on its readability has been neglected. In this article, we present the first formal user study on the readability of leader types in boundary labeling, a special variant of external labeling that considers rectangular image contours. We consider the four most studied leader types (straight, L-shaped, diagonal, and S-shaped) with respect to their performance, that is, whether and how fast a viewer can assign a feature to its label and vice versa. We give a detailed analysis of the results regarding the readability of the four models and discuss their aesthetic qualities based on the users' preference judgments and interviews. As a consequence of our experiment, we can generally recommend L-shaped leaders as the best compromise between measured task performance and subjective preference ratings, while straight and diagonal leaders received mixed ratings in the two measures. S-shaped leaders are generally not recommended from a practical point of view.