Map Warping for the Annotation of Metro Maps

We augment schematic maps of transportation systems by superimposing them on street-level maps that are fitted using image warping techniques. While schematic maps are successful in conveying information about lines and connections in a public transportation network, they usually contain little or no detail describing the environment of stations or their embedding in the surrounding area. The annotation of a distorted city map therefore alleviates this deficiency and improves further the usability of schematic transportation maps by merging two different navigational spaces. Our technique for fitting the street map to the schematic map is based on moving least squares in combination with an overlap control technique. We thus obtain an easily readable transportation network map on which we can show all the typical city map features such as rivers, streets, and parks without compromising on the schematization. Furthermore, for the interactive exploration we couple zooming with warping and control over the level of detail in what we call warping zoom.