TRAP5 – map entrance to the cultural encyclopaedia of Denmark

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In the past 4 to 5 months, I’ve been working part-time on representing the entries of the Danish cultural encyclopaedia on a map. It was challenging in two ways, because I had to work with historic administrative data (we were digitising the previous edition, published in 1953) but also because I could only use non-geographic specific servers (to limit the maintenance and facilitate the future of the platform).

Trap5 - map entrance

Although the content of Trap5 is only opened to subscribers of the edition that is currently written, the map can be explored by everyone.


I pondered for a long time at which javascript library – leaflet, openlayer, or GoogleMaps – would be best suited for this platformed. I wanted the project to be open source and fast since we could not rely on any GIS server. I eventually decided to go for openlayer 3 (OL3), even though most of the support provided by GST (now SFDE, the Danish mapping agency) was either for Openlayer 2 or Leaflet.

I used the very good sidebar plugin, sidebar v2, available for the main interactive mapping javascript libraries. For me, it was the easiest way to make my interface mobile friendly while user-friendly.

Data source


I connected to two webmapping services provided by SFDE: a historic topographic map from the 1950s, to put our data into context, and to the current road map.

Administrative maps

I used the really impressive historic administrative database of Denmark: Digdag. Visit their website, you will see every type of administrative limits: judiciary, clerical, state, and so on. Since it’s historic data, some of them have disappeared now, but every single change has been recorded. Totally impressive, since for every single day of the year, for the past 350 years, we know exactly in which administrative unit was every corner of present-Denmark.

Trap5 had been organised following the geographic regional units (Amt, herred, and cities), and the clerical local units (sogn). It wasn’t the exact use of it though, because Trap5 had also decided to use some of the historic limits from Trap4 for instance. The data also was insanely complex, full of enclaves, which means I had to do a lot of data cleaning after any data processing.


The platform has a few features: it is possible to search by current address (based on the address-API by DAWA), or to locate your own device by geolocalisation, or to see the GPS coordinates.

Every administrative unit is linked to its section in the book, so after searching the map, you can read the description of any place from Trap5. The infowindow also shows in which book (bind) it can be found, the page number, as well as some statistic of number of counties (herreder), cities (byer), and parishes (sogne).



I’m now working on the version for Greenland and Faeroes.


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