Friday 20 March 2015

Nordryggen on skis for 25 days - creating a route map

I’m currently doing my last preparations for a 25 days skiing trip across Nordryggen in Norway. It will of course depend on weather, snow conditions and blisters, but hopefully the conditions will be bearable. Norway has a great network of 500 cabins maintained by the Norwegian Trekking Association. The longest connected cross country skiing track I’ve found is around 500 km, - how to map it?

The map we're going to create with QGIS and CartoDB. Data from the Norwegian Mapping Authority.

Nordryggen (“the north ridge”) is a fairly new name of the 1,700 km mountain range that runs through the Scandinavian Peninsula. My plan is to ski around 500 km in the southern part of Norway, most of it above the tree line.

Cross-country skiing in Jotunheimen. Photo: Bjørn Sandvik

You can study the waymarked ski routes on, or download the data from the Norwegian Mapping Authority if you want to map it yourself.  The dataset is available as a PostGIS dump or in SOSI. SOSI is a common vector data format used to exchange geographical information in Norway, and not very well supported by various mapping applications. Luckily we have Sosicon, a great open source converter by Espen Andersen. I ran this command on the SOSI file:

./sosicon -2shp Tur\ og\ friluftsruter.sos 

In return I got 4 shapefiles for ski routes, hiking trails, bike trails and POIs.

If you open the ski routes shapefile in QGIS it won’t tell you much without a basemap. Let's use the map tile service from the Norwegian Mapping Authority. In QGIS, click on the “Add WMS/WMTS Layer” button in the left toolbar. Click the “New” button to create a connection. Add a name and copy this URL:

Click “OK” and “Connect”. You will now get a long list of layers in different map projections. I recommend using “norges_grunnkart” or “topo2” (detailed) in ESPG:32633 (UTM 33).

Click on “Add” and you should see a topographic map of Norway. Now you can add the shapefile, and the ski tracks will show on top.

Waymarked ski routes shown in QGIS with my route selected between Sota Sæter and Ljosland.

I selected the track segments I plan to follow, and saved the selection in a new route shapefile. I want to have the route as a continuous line with the coordinates in order, as this will allow me to use it for navigation with my GPS unit (see my next blog post). I'm using the "Join multiple lines" plugin to get the desired result.

Installing plugins is very easy with the QGIS Plugin Manager. After installation, you'll find the "Join multiple lines" plugin in the Vector menu. 

You can use the Field calculator to calculate the length of the continuous track:

This outputs a length of 505 km.

Let's move on to CartoDB to create the route map. First, I'm uploading the zipped route shapefile to CartoDB. I've also created a table with the cabin name and positions along the route.

Create a new visualzation and add the route and cabin tables. You can add the same basemap as we used in QGIS with this URL:{z}&x={x}&y={y}

The cabins are styled differently depending on the zoom level. This is the final map:

All data is available on GitHub. Map data from the Norwegian Mapping Authority.

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