Eurographics Conference on Visualization (EuroVis) 2013 B. Preim, P. Rheingans, and H. Theisel (Guest Editors) Volume 32 (2013), Number 3 Spatially Efficient Design of Annotated Metro Maps Hsiang-Yun Wu 1 , Shigeo Takahashi 1 , Daichi Hirono 1 , Masatoshi Arikawa 1 , Chun-Cheng Lin 2 , and Hsu-Chun Yen 3 1 The University of Tokyo, Japan 2 National Chiao Tung University, Taiwan 3 National Taiwan University, Taiwan (a) (b) Figure 1: Wheelchair accessible stations in Prague metro. (a) Octilinear and (b) orthogonal annotated maps. Abstract Annotating metro maps with thumbnail photographs is a commonly used technique for guiding travelers. However, conventional methods usually suffer from small labeling space around the metro stations, especially when they are interchange stations served by two or more metro lines. This paper presents an approach for aesthetically design- ing schematic metro maps while ensuring effective placement of large annotation labels that are sufficiently close to their corresponding stations. Our idea is to distribute such labels in a well-balanced manner to labeling regions around the metro network first and then adjust the lengths of metro line and leader line segments, which allows us to fully maximize the space coverage of the entire annotated map. This is accomplished by incorporating ad- ditional constraints into the conventional mixed-integer programming formulation, while we devised a three-step algorithm for accelerating the overall optimization process. We include several design examples to demonstrate the spatial efficiency of the map layout generated using the proposed approach through minimal user intervention. Keywords: Metro maps, annotation labels, efficient space coverage, mixed-integer programming 1. Introduction Schematic representation of metro maps significantly im- proves the visual readability of the map contents due to its clear and simplified layout design, especially for guiding complicated metro networks. Currently available metro maps usually follow the aesthetic criteria invented by Beck [Rob03], where the metro lines are aligned to horizon- tal and vertical directions and optionally 45 degree diagonal directions. In addition, annotating the map with comprehen- sive explanations and photographs effectively allows us to find sufficient information on our own places of interest. Ac- tually, this type of schematic representation with such large annotation labels has been widely employed in commer- cially available metro maps and travel guidebooks [Gui12]. c  2013 The Author(s) Computer Graphics Forum c  2013 The Eurographics Association and Blackwell Publish- ing Ltd. Published by Blackwell Publishing, 9600 Garsington Road, Oxford OX4 2DQ, UK and 350 Main Street, Malden, MA 02148, USA. DOI: 10.1111/cgf.12113