In recent years, the usage of zoomable web maps have increased strongly. Analog maps had one scale, nowadays OpenStreetMaps or Googles up 20 zoom levels for raster tiles. Raster web maps had only a number of predefined zoom levels, while now vector maps offer continuous zooming. With the for user comfortable switching of the zoom levels arise problems for cartographers: It is a complex task to produce such maps and need special knowledge, which is just under development.

As result of the automated rule based map production were developed new strategies for mapping and graphical symbolisations. In Addition for all these digital maps exists no legend, because of the changeable scale and its effort for a manual creation. In the case of the OpenStreetMap project, the rendering software called Mapnik and is used in combination with a PostGIS database to produce raster tiles. The design of the “OSM-Carto” Style is defined in various configuration files and hosted in GitHub repository. Our idea is to develop a software that produce a legend for all zoom levels. We call this a multiscale legend. It should consist out of matrix with the symbols depending on the zoom level for all features. The production should occur fully automated using the style files.

Your task will be the implementation and improvement of the routines for the production of such a legend. For the implementation, you have to learn how to work with the Mapnik software and to documented there usage in mapping projects and developed strategies for digital map design. You have the possibility to bring in your own ideas and the further development of a good piece of software for OpenStreetMap. You can find a manual produced prototype example of a multiscale legend in Figure 1. We aspect some knowledge in programming languages like Python otherwise, the willingness to familiarize oneself with them. The resulting software should be freely available on GitHub and transferable to other mapping projects that uses Mapnik.

Contact
Place: TU Dresden – Institute for Cartography
Supervisors: Prof. Dr.-Ing. Dirk Burghardt / M.Sc. Mathias Gröbe
Room: HÜL West 134 / HÜL West 140
Telephone: +49 351 463-36200 / +49 351 463-33099
Email: dirk.burghardt@tu-dresden.de / mathias.groebe@tu-dresden.de