Paper Maps as an Entry Point for Tourists to Explore Wikipedia Content Johannes Schöning Institute for Geoinformatics University of Münster Robert-Koch-Str. 26-28 48149 Münster, Germany j.schoening@uni- muenster.de Michael Rohs Deutsche Telekom Laboratories TU Berlin Ernst-Reuter-Platz 7 10587 Berlin, Germany michael.rohs@telekom.de Antonio Krüger Institute for Geoinformatics University of Münster Robert-Koch-Str. 26-28 48149 Münster, Germany antonio.krueger@uni- muenster.de ABSTRACT In this demonstration we present a mobile tourist guide. It makes geographically referenced Wikipedia content accessi- ble via camera phones, which are used as magic lenses for pa- per maps. Visual and auditory output is controlled by mov- ing and rotating the phone over a paper map. Many people still use paper maps, because they provide high-resolution, large-scale information with zero power consumption. A drawback of paper maps is that they neither provide per- sonalized nor dynamic information. In our approach we augment paper maps with geospatial content using cam- era phones as see-through tools. The dynamic content is retrieved from Web 2.0 applications like Wikipedia, which aggregate contributions from many users. 1. INTRODUCTION AND RELATED WORK Many different forms of maps and other geospatial content can be found on the Internet today and mobile map ap- plications are rapidly growing. Because of the drawbacks of visualizing maps on mobile devices (small display, low resolution) the combination of mobile devices with external paper maps is an active research area. Nokias Map Navigator is an application that allows the user to view and scroll a map on the screen using the concept of sensing motion detection through the camera. MapSnapper 1 is an application that takes a picture of a paper map and sends it to a central server for analysis. The resulting map, which is sent back to the user, contains details on all nearby points of interest. A drawback is that the system does not work in real-time. Reilly et al. [5] use maps equipped with an array of RFID (Radio Frequency Identification) tags to realize the link to the paper map. Their work provides ad- ditional geospatial information for special points of interest. Disadvantages of this approach are the low spatial resolu- 1 http://www.iam.ecs.soton.ac.uk/news/1038 tion (because of the size of the RFID tags) and the high map production costs. The method was enhanced by using computer vision techniques [5], resulting in a higher spatial resolution and enabling more interaction techniques. In previous work [9] we introduced a method that uses an op- tical marker for map interaction. This allows for the display of additional geoinformation, such as georeferenced vector or raster data, on the map. One disadvantage of this ap- proach is that valuable map space is obscured. Subsequent work addressed this problem: In order to align the overlay graphics with objects in the camera view, the video stream of the camera is continuously analyzed. The position of ob- jects on the map has to be tracked in order to accurately align the graphical overlays with the real-world view. To simplify the task of real-time markerless tracking on a de- vice with limited computing resources, the map is modified in our prototype setup: it contains black dots arranged in a regular tiny grid. With the correlation between a precom- puted map and the camera image, the system computes the actual position of the mobile device over the map. Using this technique we implemented several applications. Wikeye [3] is an approach to improve the understanding of places that combines digital Wikipedia content with a paper- based map. A city map of Berlin, Germany, is being used as a test case for this application. When the user views a small portion of a Berlin map through her mobile device – for example, the area containing the Reichstag building and the Brandenburg Gate – Wikipedia-derived content relating to these spatial objects is offered to the user. Rotating the device slightly about the camera axis switches to a differ- ent time in history and delivers an overview on data related to that time period. Depending on the spatial extent of the map visible on the camera phone, the system responds by offering Wikipedia data about spatial objects with larger area footprints. In other words, as the cartographic scale de- creases, the threshold area for a spatial object to be featured within Wikipedia data increases. Wikear [8] provides a narrative-based guided audio tour be- tween the location of the city map and the destination se- lected by the user. The user can then listen to the story as she travels to the destination. This audio tour can be retrieved and personalized interacting with a paper map.