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

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.

Keywords

• label placement
• real-time processing
• area feature labeling
• auxiliary line