Implementation and Evaluation of a Fast Area Feature Labeling Method Using Auxiliary Lines

Noboru Abe,Kohei Kuroda,Yosuke Kamata,Shogo Midoritani

doi:10.3390/ijgi9090529

Noboru Abe, Kohei Kuroda + Show 2 more

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https://doi.org/10.3390/ijgi9090529

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Abstract

Appropriate place labels, which provide the name or attribute of a graphical feature, are important in geographical information systems and cartography. Herein, an internal label placement method was proposed for area features, such as cities, prefectures, and lakes, on a map. For internal label placement, placing a large label for an extremely narrow or small area, such that the label does not protrude from the corresponding area is challenging. In such cases, a label can overlap with protruding labels from other areas. Meanwhile, tablet devices have been rapidly employed in recent years. Because tablet devices can easily zoom in on a map, it is possible to eliminate the overlaps by enlarging the map without changing the label size. Therefore, we proposed a method that enables real-time processing, even on tablet devices. The label positions are determined by detecting the intersections of the auxiliary and boundary lines of a given area feature. The proposed method adequately labels the positions of area features, even those with indents and narrow sections. Moreover, it can find tens of thousands of label positions within 100 ms, even on low-performance computers, such as tablet devices.

Highlights

This paper proposes a real-time method for placing the labels of area features, such as cities, prefectures, and lakes on a map displayed on a tablet device screen
Each area feature A is described by a polygon and it is assigned a label of specified size, which corresponds to a name or attribute
The appropriate placement of graphical feature labels is important for geographical information systems and cartography

Summary

Introduction

This paper proposes a real-time method for placing the labels of area features, such as cities, prefectures, and lakes on a map displayed on a tablet device screen. Each area feature A is described by a polygon and it is assigned a label of specified size, which corresponds to a name or attribute. The proposed method places the label inside the corresponding area feature A. It can find an adequate label position even for area features with indents and narrow sections. The appropriate placement of graphical feature labels is important for geographical information systems and cartography. A label placement inside A should avoid the near-boundary regions or narrow sections of A. Placing most of the label outside A is undesired, but may be unavoidable when A is very small

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